An installation to generate mechanical energy using a combined power cycle

ABSTRACT

This invention refers to an installation for the generation of mechanical energy using a Combined Power Cycle which comprises, at least;means to implement a closed or semi-closed regenerative constituent Brayton cycle which uses water as thermal fluid,means to implement at least one Rankine cycle, the constituent basic Rankine cycle, interconnected with the regenerative constituent Brayton cycle, anda heat pump (UAX) which makes up a closed circuit that regenerates the regenerative constituent Brayton cycle;as well as the procedure for generating energy through the use of the cited installation.

FIELD OF THE INVENTION

The field of application of the invention lies in the industrial sectordedicated to generating mechanical energy for use and conversion intoother types of energy.

STATE OF THE ART

At the moment, the so-called “combined cycles” are one of the mostefficient and eco-friendly technologies for generating energy thatexist. A combined cycle is a procedure for generating energy byassociating two coupled thermodynamic cycles to enhance the performance.

In the current state of the art for combined cycles to generatemechanical energy and its possible transformation into other types ofenergy, there is a need to improve the efficiency and reduce thedischarges of greenhouse gases into the atmosphere.

One installation to implement a combined cycle consists of a gas turbineoperating an open Brayton cycle in which the hot exhaust gases passthrough a heat recovery boiler, where steam is generated which isapplied to a turbine that generates additional mechanical work followingan independent Rankine cycle.

The most common combined cycle power plants work with gas turbines whichtake in outside air which, after pressurisation in a compressor, passesto a combustion chamber where the fuel is burned. The exhaust gases fromthis leave the burner at a high temperature with excess air,constituting the thermal fluid of an open Brayton cycle, which isexpanded in a gas turbine, generating mechanical work. Finally, theturbine gases leave the boiler and are expelled to the atmospherethrough a chimney.

The fact that a compressor takes in outside air and that the combustiongases end up discharged into the atmosphere without returning to thecycle means that these are open Brayton cycles, because there is aninterchange of matter with the atmosphere.

Therefore, and despite their simplicity, these open cycles have thedrawback that they imply the emission of polluting gases, as thecombustion products end up discarded into the atmosphere. Thesepolluting gases are fundamentally CO2 and NOx (always provided that thecomposition of the fuel is sulphur-free). The proportion of CO2discharged during combustion depends directly on the kind of fuelburned. Currently, natural gas is the most commonly used fuel in theindustry in gas turbines because, among other reasons, the methane thisfuel contains is the hydrocarbon which produces the least CO2 per unitof work generated.

Moreover, the production of NOx increases fundamentally as thecombustion temperature does. Obviously, this creates a conflict ofinterest with a trade-off between efficiency and environmental impact,as according to the principles of thermodynamics, increasing thecombustion temperature boosts performance, but this on the other handleads to a rise in the emissions of NOx.

The ultimate objective, which would overcome the problems afflicting thestate of the art, is to devise a cycle which basically producesmechanical energy, that does not emit any greenhouse gases into theatmosphere and which offers better performance than what is currentlyobtained in other conventional combined cycles.

This invention refers to an installation to execute a combined cycleprocess which uses water as thermal fluid, to generate mechanicalenergy, and which is specifically devised to operate a closed cycle, orto perform a process based on internal oxy-combustion in which there isat least one Rankine cycle which operates in an integrated way with aBrayton cycle variant which is regenerated using a heat pump whichinterchanges this heat energy (between the Brayton cycle and the heatpump there is no interchange of material), and in such a way that bycombining the two cited constituent cycles, mechanical energy isgenerated with no need to emit greenhouse gases into the atmosphere.

One alternative for avoiding the emission of polluting gases into theatmosphere consists of using combined cycles which operate as closedcycles. In other words, in these cycles the thermal fluid isrecirculated and does not need to be replenished, and nor does it comeinto contact with the atmosphere. Nevertheless, whenever the heat sourceof the cycle is energy from internal combustion, certain chemicalreactants (fuel and comburent) must be added continuously, while it isnecessary to eliminate the products generated by the chemical combustionreaction from the cycle. This poses important economic, technical andenvironmental challenges, especially in relation to the continuousseparation of the combustion products within the gaseous phase whichacts as thermal fluid. Another drawback is that, as air is not used ascomburent, closed cycles require pure oxygen to carry out the process ofcombustion, and so they depend on some kind of auxiliary process whichfurnishes this.

An effective way to raise the efficiency of the Brayton cycle is by“Regeneration”, with which part of the heating of the cycle is carriedout using a source of heat internal to the cycle itself.

As a result of “Regeneration”, we attain improved performance for thecycle because the amount of external heat which must be supplied to thecycle is reduced, while the amount of waste heat the cycle releases intothe environment is reduced.

The term “Regenerative Brayton Cycle” refers to a Brayton cycle whichrecovers some of the heat given off by the hot gases after the turbineand transfers it, using a heat exchanger, to the compressed gases priorto their entry into the burner. Nonetheless, this method of regenerationis not the only one, as it is also feasible to “regenerate” a Braytoncycle using any other procedure capable of recouping heat from some partof the cycle to reintroduce it back into the process.

One of the innovative aspects of this invention is that it includes themeans necessary to implement a regenerated Brayton cycle using a “heatpump” connected to one or more Rankine cycles, giving rise to a combinedcycle installation with unusual characteristics. In thermodynamics, a“heat pump” is defined to be any refrigerating machine which takesthermal energy from one body and transfers it to another which is at ahigher temperature, thanks to an amount of energy supplied from outside(generally as mechanical work from compression). It can be consideredfor all purposes that a refrigerating machine is the same thing as aheat pump, and the two terms are employed without distinction, orconsidering the intended application.

At an industrial level, there exist two types of refrigerating machinesor heat pumps, depending on the type of technology they employ:compression refrigerating machines and absorption refrigeratingmachines. These two types of machine (compression or absorption) have incommon that both have a condenser (hot reservoir) and an evaporator(cold reservoir) separated by an expansion device. However, they differin the manner and type of energy used to make the cold and hotreservoirs operate at different pressures.

Compression refrigerating machines use a gas compressor which consumesmechanical work taken from outside, whereas what absorption machinesrequire to operate, basically, is a supply from an external heat source,and these machines are based on the physico-chemical principle ofabsorption/desorption of a gas in a liquid.

Conventional “absorption” machines can dispense with a compressor,because an “Absorber/Generator” system, with no need for mechanicalmeans, looks after generating the differential pressure which isrequired, by making the absorber and evaporator work at a lower pressurethan that of the generator and condenser.

Instead of needing compression work to operate, absorption machinesrequire an additional amount of heat to carry out the operation of“desorption” (evaporation of the dissolved gas). Ultimately, thisadditional amount of heat is eliminated when the reverse process of“absorption” takes place. This additional loss of heat is the reasonwhy, comparatively speaking, absorption machines lose and require moreenergy to work than compression machines, so that their energyefficiency always turns out to be relatively low. Nevertheless,absorption machines do have the advantage that, except for the solutionpump, they need virtually no mechanical work to operate.

The applicability of a “heat pump” to assist the regeneration in theCombined Cycle of the system is severely limited by a series ofinescapable thermodynamic constraints, on the one hand, and on theother, by the particular requirements of the operation demanded of it.In other words, a Brayton cycle cannot be regenerated with just somearbitrary heat pump.

For a certain heat pump to be helpful to “regenerate” a Brayton cycle asis proposed here, it must satisfy the following requirements:

-   -   the “cold reservoir” of the heat pump must work at temperatures        close to that of the condensation of water vapour at atmospheric        pressure.    -   the temperature difference between the cold and hot reservoirs        must be sizeable (several tens of degrees Celsius) to regenerate        a vapour at a pressure significantly greater than that at which        is was previously condensed.    -   the mechanical compression energy must also be taken from and        returned to the Brayton cycle which is being regenerated.    -   the performance of the cooling cycle must be sufficiently high        for this manner of regenerating part of the Combined Cycle to be        worthwhile.

The installation working according to the Combined Cycle which is theobject of this invention offers, on the one hand, greater efficiencythan that of conventional combined cycles and on the other hand, anintrinsic capture of the CO₂ (carbon dioxide) when any of the thermalSources providing heat to the Combined Cycle is made up of a burner. Theinstallation of the invention and the procedure conducted with itimplicitly offer a carbon dioxide separation-capture system.

It is understood that a Combined Cycle “intrinsically captures CO2” whenthis gas from combustion is obtained by a single point of the cycle,concentrated and confined (whether in liquid or gaseous form), withoutany specific additional process other than the normal functioning of thecycle itself for generating useful energy being required. When fuels areused as a source of energy, the functioning of the installation itselfseparates and confines the polluting gases and prevents them from cominginto contact with the atmosphere. On the other hand, when water isgenerated as a combustion product, this, on the other hand, iseliminated from the Combined Cycle in liquid phase and at ambientpressure.

In conventional combined cycles, each constituent cycle (Brayton andRankine) uses a particular thermal fluid and, specifically, its Braytoncycle exchanges matter and energy with the atmosphere.

On the other hand, the constituent Brayton cycle and the constituentbasic Rankine cycle which comprise this Combined Cycle work in a coupledmanner, exchanging matter (given that both use water as common thermalfluid) and energy, in such a way as to make up a single Cycle in its ownright for the generation of mechanical energy and with unusualcharacteristics.

One characteristic of this Combined Cycle is, if we except theinevitable “real losses”, heat is only lost to the outside through asingle heat sink, and as a consequence, better performance is obtainedthan in other conventional combined cycles.

Considering that the constituent Brayton and Rankine cycles making upthe Combined Cycle of this invention possess particular characteristicswhich set them apart from these thermodynamic cycles in certainessential aspects, the terms “Brayton cycle” and “Rankine cycle”, whenreferring to the sections which comprise the overall Combined Cycle, arenot strictly correct, because they differ from these cycles in certainfundamental ways (for example, Brayton cycles, by definition, do notwork with a condensable fluid). Nevertheless, it is the case the theCombined Cycle of this invention consists of variants or modificationsof the two cycles—Brayton and Rankine- and they do work in a mutuallyinterconnected way. This is why in this report we refer to thesemodified Brayton and Rankine cycles, always accompanied by the word“constituent”, to prevent confusion and facilitate comprehension andidentification of the components being referred to.

Definitions

UAX: Absorber unit for exchanging heat. This is the system whichperforms the duties of the “heat pump”, assisting in the regeneration ofthis Combined Power Cycle. The UAX, as an independent operational unit,is identified by the number (200). It is employed to regenerate theconstituent Brayton cycle. The UAX (200), although it does notinterchange matter with the Combined Power Cycle, works in “symbiosis”with it, and is an indispensable system for the Combined Cycle for thegeneration of mechanical energy to work. The UAX is an essentialcomponent of the installation of the invention which works with ammoniaand water.

Concentrated solution: this is the solution of ammonia in water whichemerges from the Absorber.

Dilute solution: this is the solution of ammonia in water which emergesfrom the Generator (201).

Intermediate concentration solution: this is the solution of ammonia inwater which emerges from the Generator (202) and which enters theGenerator (201).

Combined Cycle: Unless otherwise specified, the term “Combined Cycle”refers to the cycle which is the object of this invention, whose purposeis to obtain mechanical energy from heat energy. In this report, theterms “Combined Cycle”, “Power Cycle” and “Combined Power Cycle” areused without distinction. The term “conventional combined cycle” isemployed herein to refer to any possible combined cycle from the currentstate of the art.

Regenerative Cycle: This is a cycle with a system of heat exchangers to“regenerate” it, in that some of the heating of the cycle is carried outusing a source of heat internal to the cycle itself.

Constituent Brayton Cycle: This is the part of the Power Cycle of thisinvention which is regenerated by the Heat Pump UAX (200). Thefunctioning of this part of the Power Cycle is based on a modificationto the Brayton cycle, which in this invention possesses particularspecific characteristics as a condensable fluid (water) is used, itworks interconnectedly with a Rankine cycle and it is regenerated by aHeat Pump UAX (200).

Constituent Basic Rankine Cycle: This is the part of the Power Cycle ofthis invention which is driven by the Feedwater Pump (119) and by theTurbine TAP (122). The functioning of this part of the Power Cycle isbased on a Rankine cycle, although in this invention the “Basic RankineCycle” possesses particular specific characteristics as it worksinterconnectedly with a “Constituent Brayton Cycle” and the two sharecertain common elements. The Constituent Basic Rankine Cycle is anessential part of the Power Cycle.

Secondary Rankine Cycle: This is an auxiliary Rankine cycle: in otherwords, it is not a system essential to the Power Cycle. In theconfigurations of the Combined Cycle which have a “Secondary RankineCycle”, its Condenser (128) always performs the essential function of“heat sink”. The “Secondary Rankine Cycle” is characterised by havingits own Turbine TBP (127) and because it always works at lower pressurethan the Constituent Basic Rankine Cycle.

Open cycle: This is a cycle in which the thermal fluid is not recycled,but must be renewed constantly. In open cycles, there exists at leastone point where fluid enters from outside, and another where fluidleaves the cycle to the outside.

Closed cycle: Cycle in which thermal fluid neither enters nor leaves, inwhich the supply of outside heat always takes place through heatexchangers, so there is no interchange of the fluid material in thecycle with the outside. The Combined Power Cycle is closed when itcontains no burner which provides energy to it.

External combustion cycle: This is a closed cycle where the sourcesupplying heat is a combustion process taking place outside the cycle.

Internal combustion cycle: This is a closed cycle where the sourcesupplying heat is a combustion process in which the products of thechemical reaction make up or form part of the thermal fluid.

Oxy-combustion: This is a combustion process in which the comburent usedis not air, but rather pure oxygen diluted in the thermal fluid itself(water vapour in this invention).

Semi-closed cycle: In this invention, this term is used for a cyclewhich is simultaneously an internal combustion and oxy-combustion oneand in which, moreover, the thermal fluid is recycled once thecombustion products have been eliminated from it.

CoP: The CoP (Coefficient of Performance) of a “heat pump” is defined tobe the ratio or quotient yielded by dividing the useful heat energytransferred by the energy added to achieve this. In other words, the CoPis the coefficient determining the performance of any refrigeratingmachine. The notion of CoP changes according as the machine is acompression one (in which the energy added is the mechanical workconsumed by the compressor) or an absorption one (in which the energyadded is basically heat supplied to the generator).

Installation: Mechanical energy generator arrangement made up of theCombined Power Cycle and the Heat Pump UAX (200).

Heat exchanger element: Either of the sides making up a heat exchanger,without regard to whether it receives or gives off heat. Any heatexchanger is made up of at least two elements. In this invention, theterm “Element”, accompanied by the number which identifies itexplicitly, is used for brevity. In this invention, any heat exchangeris identified by indicating the numbers of the two or more “Elements”comprising it.

Coil: Heat exchanger element made up of tubular pipes, in any kind ofconfiguration. In this invention, this term is used to refer to theelement of an exchanger which works at higher pressure. The functioningmay under no circumstances be linked to the shape of the heat exchangerelement so referred to.

Shell Side of a Heat Exchanger: This term is employed herein to refer toan element of an exchanger which works at lower pressure, and whichcontains the Heat Exchanger Element working at higher pressure insideit.

Condensation Exchanger: This is a heat exchanger in which condensation(partial or total) of the water vapour circulating through the “ShellSide” Element takes place. This condensation heat is transferred to oneor more coils or exchanger elements to raise the temperature of thefluid circulating through them.

Heat Sink: In this invention, the term “Heat Sink” is used to denote theheat exchanger element through which the Combined Cycle gives off lostheat to outside the cycle. In the Combined Power Cycle, the “Heat Sink”is always made up of an Element (128) which produces the condensation ofvapour at the end of or after the Heat Recovery Conduit CRC (103). Whena secondary Rankine cycle is employed at this location to perform thisfunction, that auxiliary cycle will always have a final condensationelement referred to as (128) to clearly identify that this is the onlyelement through which heat is transmitted outside the cycle.

Real losses: This term refers to the inevitable irreversibilities andlosses of heat by conduction, convection and radiation in any componentcaused by the mere fact that it is at a higher temperature than itssurroundings. Given that the real losses are inevitable in any realcycle, even where not mentioned explicitly in this report, they areconsidered obvious.

In this report, although it would not be accepted as correct to do so inthermodynamics, the latent heat held in the combustion products obtainedin the Combined Cycle is also considered to be “real losses” because, inreality, these emerge at such a low temperature-liquid water on the onehand, and CO₂ from the element (107)—, that this is irrelevant or can beconsidered negligible for practical purposes.

Thermal fluid: This is the fluid which contains, circulates andtransports the energy transferred in the different elements which makeup a thermodynamic cycle.

Cogeneration: In this report, cogeneration is understood to be anoptional procedure with which, in addition to mechanical energy, anadditional amount of thermal energy is obtained which turns out to beuseful for any kind of process outside the Power Cycle itself. In thisreport, it is assumed for all purposes that the heat the Combined Cyclereleases to the outside as a result of “cogeneration” is always usefulheat and never represents a loss of energy from the cycle because it isconsidered that the installation is so designed as to take thisextraction of thermal energy from the Power Cycle into account: thiswould take place in accordance with specific requirements and subject tothe temperature specifications imposed by the external consumptionsystem for which this heat is intended.

Useful energy: This term is considered to be the sum of the heat for useexternal to the cycle as “cogeneration” plus the net mechanical workgenerated by the Power Cycle.

Power shaft: the power shaft (130) is made up of the assemblage ofmechanical elements with which the machines of the Power Cycle and theHeat Pump UAX, receive or provide mechanical energy.

Physically, the power shaft need not be necessarily constituted of acommon mechanical shaft to which all the turbo-machines of the cycle arecoupled, as there is also a feasible option of coupling each compressorto an independent motor, with each turbine coupled to its correspondingelectricity generator. Nonetheless, using this notion of power shaftfacilitates comprehension, as it is considered that the net mechanicalwork of the Combined Cycle is obtained from the power shaft (130) as theresult of summing all the mechanical work of the machines comprising it(with their signs).

Industrial pure oxygen: The term “Industrial pure oxygen” is used inthis report to refer to this gas when, under its supply conditions, itmeets the international standards to be considered “industrial-qualitypure oxygen”. It is considered evident that. even though they areundesirable, traces of impurities will always accompany the oxygen as acomburent for industrial use.

Supercritical pressure and temperature: These are conditions of pressurean d temperature higher than the critical point for a given substance.The critical point is that at which the densities of the vapour and theliquid are the same.

Ambient pressure: The term “ambient pressure” is used herein to refer toa range of pressure corresponding to the saturation pressure of watervapour between 80° C. and 120° C. That is to say, ambient pressure isconsidered to be the range of pressures from 0.5 bars to 2.0 bars,approximately.

Bar: absolute bar

DESCRIPTION OF THE FIGURES

This report includes five figures. The first four are schematicrepresentations of the different configurations or design versions ofthe Combined Power Cycle presented. Finally, the fifth figure is aschematic representation of the configuration of the “Absorber unit forexchanging heat” (UAX), which performs the essential function ofassisting the Power Cycle as a “heat pump”.

FIG. 1 shows the conceptual design version of an “Essential CombinedCycle” according to Configuration-1 which has the elements indispensablefor the Combined Cycle to be able to function assisted by a heat pump(UAX), pursuant to this invention. Whatever may be the designconfiguration of the Power Cycle, it contains all the essential elementsincluded in this FIG. 1, on which grounds these components are deemed“essential”.

FIG. 2 shows schematically the design version of the installation toimplement the Combined Cycle for the generation of mechanical energyaccording to Configuration-2 of the invention, which includes, inaddition to the essential equipment of the cycle (shown in FIG. 1), theelements which confer improved efficiency upon the Combined Cycle, withthe particular feature that it works at a pressure above atmosphericpressure throughout the Heat Recovery Conduit (CRC) (103). In the finalsection of the CRC (103), vapour is generated in a secondary Rankinecycle which uses its own thermal fluid independent of the rest of thePower Cycle. This configuration supposes that, within the CRC (103),there exists a final conduit section where partial condensation of thewater vapour circulating in it to generate vapour in the secondaryRankine cycle takes place.

FIG. 3 shows schematically the design version of the installation toimplement the Combined Cycle for the generation of mechanical energyaccording to Configuration-3 of the invention, which includes, inaddition to the essential equipment of the cycle (shown in FIG. 1), theelements which confer improved efficiency upon the Combined Cycle, withthe particular feature that in this configuration of the Combined Cycle,there is no condensation within the Heat Recovery Conduit (CRC) (103),and rather there is an independent Conduit (105), where partialcondensation of the water vapour circulating through it takes place.Between the two conduits, (103) and (105), respectively, there exists aFan (104) which sucks the gases and released vapour from the CRC (103)and raises the pressure in the section of the Conduit (105) that housesat least one part of the Evaporator (125) for a secondary Rankine cyclewhich uses its own thermal fluid independent of the rest of the PowerCycle.

FIG. 4 shows schematically the design version of the installation toimplement the Combined Cycle for the generation of mechanical energypursuant to Configuration-4 of the invention assisted by UAX (200) whichincludes, in addition to the essential equipment of the cycle (shown inFIG. 1), the elements which confer improved efficiency upon the CombinedCycle, which due to its simplicity is more appropriate when theinstallation is intended to work in closed cycle or when only hydrogenis used as the fuel. That is to say, when there is no presence of CO₂ inthe Power Cycle.

This configuration of the Combined Cycle has the particular feature thatit uses part of the flow of water vapour circulating through the CRC(103) to be sent directly to the Turbine (127) of a secondary Rankinecycle which uses the same thermal fluid as the rest of the Power Cycle.Moreover, the condensed water obtained from the Condenser (128) is alsoused directly as feedwater for the rest of the Combined Cycle. Thismeans that in this version of the Power Cycle, the secondary Rankinecycle does not form an independent cycle, but rather is integrated intoit, forming a single cycle.

FIG. 5 is a schematic representation of the configuration of the“Absorber unit for exchanging heat” (UAX), which performs the functionof a “heat pump”, indispensable for the operation of the Combined Cycleof this invention.

FIG. 6 shows schematically the design version of the installation toimplement the Combined Cycle for the generation of mechanical energypursuant to Configuration-5 of the invention assisted by UAX (200),which includes all the equipment of the cycle in any of itsconfigurations. It enables functioning either in closed cycle orsemi-closed cycle using any kind of fuel that the rest of theconfigurations can employ.

Configuration 5 has the same elements as Configuration-3, plus aSuperheater (136) and a Turbine (137). Configuration-5 differs fromConfiguration-3 in that one Element (112) has two additional outletcurrents (one of vapour and another of preheated feedwater). Anotherdifference is that in Configuration-5, one Compressor (115) has anadditional stage of compression compared with Configuration-3.

DESCRIPTION OF THE INVENTION

This invention refers to an installation according to claim 1, as wellas a procedure for the generation of energy according to the principalclaim of the procedure. Particular embodiments of the installation andthe procedure are described in the respective dependent claims.

This invention refers to an installation for the generation of energyusing a Combined Power Cycle which comprises, at least:

-   -   means to implement a closed or semi-closed regenerative        constituent Brayton cycle which uses water as thermal fluid,    -   means to implement at least one Rankine cycle, the constituent        basic Rankine cycle, interconnected with the regenerative        constituent Brayton cycle, and    -   a heat pump (UAX) which makes up a closed circuit that        regenerates the constituent Brayton cycle.

The installation for the generation of energy also includes an essentialHeat Source (101), selecting between:

-   -   a heat exchanger and    -   an oxy-combustion burner, such that in the cited essential Heat        Source (101), currents from the two cycles, the constituent        Brayton and the constituent basic Rankine, come together.

According to particular additional embodiments of the invention, whenthe Combined Power Cycle is semi-closed, with oxy-combustion and captureof CO₂, it comprises at least one internal combustion burner by which itreceives energy from outside.

According to particular additional embodiments of the invention, whenthe Combined Power Cycle is closed, it does not have any burners andincludes at least one heat exchanger by which it receives energy fromoutside and has no internal combustion burner.

For any of the aforementioned embodiments, the installation alsoincludes:

-   -   an element (107) which may be:        -   a regeneration condenser (107), by which the installation            transmits energy to the cold reservoir (201) of the heat            pump UAX, which condenses in one simple stage or        -   a CO₂ liquefaction plant which receives work from the power            shaft (130) and condenses gases in multiple stages and only            transfers the heat released in the successive stages of            compression of that CO₂ liquefaction plant to the cold            reservoir (201) of the UAX.    -   a Reboiler (113), with which heat is returned to the Power Cycle        from the hot reservoir (210) of the heat pump UAX.    -   a condensate regeneration Pump (111), which drives the        condensate obtained in the bottom of the Element (107), and        makes it flow towards the Reboiler (113),    -   a heat recovery Conduit (CRC) (103), in which water vapour is        generated,    -   at least two turbines, one of which is a high-pressure Turbine        TAP (122), which sends steam to the essential Heat source (101),        and another high-temperature Turbine TAT (102), which sends        vapour to the heat recovery Conduit CRC (103).    -   at least one common Power Shaft (130), from which the useful        mechanical energy of the cycle is obtained,    -   a system which performs the function of a heat Sink by        condensing vapour in the bottom of, or after, the CRC (103),    -   a condensate return Pump (109),    -   a feedwater Pump (119) for the constituent basic Rankine cycle,    -   a vapour generator for the constituent basic Rankine cycle        consisting of:        -   economiser Coils (120),        -   Evaporators and Superheaters for the water vapour (121)            situated inside the CRC (103),    -   one condensation heat exchanger Element (106), before the entry        of vapour and gases to the Element (107), which relinquishes        heat to a condensate return Preheater (110),    -   one condensation heat exchanger Element (114), provided at the        outlet of the Reboiler (113), which relinquishes heat to    -   a bypass line which joins the constituent Brayton cycle with the        constituent basic Rankine cycle, situated at the Element (112),        selecting between:        -   a Preheater (112) for the intake water to the Reboiler (113)            itself,        -   and a heat recovery exchanger (112), which in addition to            preheating the intake water for the Reboiler (113) itself,            can heat the feedwater to the Pump (119) and generate vapour            which can be directed to the compressor (115) and/or a            turbine a heater (137) once its temperature has been raised            in a Superheater (136)    -   between the impulsion of the regeneration condensate Pump (111)        and the aspiration of the feedwater Pump (119).

In the event that the constituent Brayton cycle is semi-closed, usesoxy-combustion, and in the case that fuels with carbon are used, theinstallation includes:

-   -   an outlet for the CO₂ produced in the combustion, situated in        the regeneration Condenser (107) in gaseous state or liquid        state if the regeneration Condenser (107) is a liquefaction        plant, and    -   an outlet for the liquid water produced by the combustion in the        condensate return line.

In the event that in the installation for generating energy, the Braytoncycle is closed, or in the case that it uses solely hydrogen as fuel,the heat sink can consist of a secondary Rankine cycle which uses thesame fluid as the rest of the Power Cycle, and is interconnected withthe installation through the CRC (103) and the condensate return Pump(109).

In any of the foregoing embodiments, the installation for generatingenergy may include, apart from the essential Heat Source (101), anothersupplementary heat source (132) which provides extra heat to the PowerCycle from outside (this could be an exchanger or pressurised burner),situated between the final Superheater (121) and the Turbine TAP (122).

In any of the foregoing embodiments, the installation for generatingenergy may include, in addition, one (115) or several vapour compressors(117), connected in series, situated at the vapour outlet of theexchanger Element (114), and before the vapour intake of the essentialHeat Source (101).

In any of the foregoing embodiments, the installation for generatingenergy may include, in addition, a vapour cooling exchanger (116/118)between the compressors connected in series, (115) and (117).

In any of the foregoing embodiments, the installation for generatingenergy may include, in addition, in the condensate line which emergesfrom the bottom of the condensation exchanger Element (114), a returnline to the Reboiler (113).

In any of the foregoing embodiments, the installation for generatingenergy may include, in addition, an additional exchanger provided at thevapour intake of the heat recovery

Conduit (103) to generate heat which could be used outside theinstallation, useful, among other things, for applications ofcogeneration, using a heat exchanger Coil (133).

In any of the foregoing embodiments, the installation for generatingenergy may include, in addition, a heat exchanger Element forcogeneration (133) provided inside the heat recovery Conduit (103), fromwhich it extracts useful heat energy which could be destined forexternal use in any type of industrial application.

In any of the foregoing embodiments, the installation for generatingenergy may include, in addition:

-   -   a Fan (104), which takes the outlet vapours from the heat        recovery Conduit CRC (103) and compresses them for sending to a        condensation exchanger Element (105), in which at least one        component section of the evaporator (125) of an independent        secondary Rankine cycle is housed.

In the embodiment mentioned in the previous paragraph, the installationfor generating energy may include, in addition:

-   -   a heat Exchanger (108/124) in which, on the shell side (108),        the condensate from the Conduit (105) is cooled, and in whose        interior there is housed an economiser (124) of the independent        secondary Rankine cycle.

In any of the foregoing embodiments, the Heat Pump UAX (200) of theinstallation includes:

-   -   a main Generator (201) of gaseous ammonia, acting as cold        reservoir, which exchanges heat solely with the Element (107),    -   a secondary Generator (202), which receives an ammonia solution        from an Absorber (210), and sends the ammonia vapour to some        Compressors (203), while the remaining ammonia solution is sent        to the main Generator (201),    -   at least two ammonia Compressors (203), connected in series,        with cooling in between, which receive ammonia from the main        (201) and secondary Generators (202)    -   a compressed ammonia Condenser (207) which receives the ammonia        compressed and cooled in a supercritical ammonia Evaporator        (209), and transmits the heat to the secondary Generator (202),    -   a supercritical ammonia Evaporator (209),    -   a Pump (208) for ammonia condensate from the compressed ammonia        Condenser (207), which impels it to the ammonia Evaporator        (209), where ammonia vapour is produced at supercritical        pressure,    -   an ammonia Absorber (210), which receives the vapour from the        Evaporator for supercritical ammonia (209) and dissolves it in        an aqueous phase, and    -   a transfer Pump (215) which transfers the dilute ammonia        solution from the main Generator (201) to the Absorber (210).

The Heat Pump UAX (200) may additionally include:

-   -   a heat Exchanger (213/214) between the dilute ammonia solution        from the main Generator (201) and the concentrated ammonia        solution from the Absorber (210),    -   a Coil (211) housed inside the ammonia Evaporator (209), which        harnesses the heat contained in the concentrated ammonia        solution from the Absorber (210), to produce supercritical        ammonia,    -   a cooling Coil (206) for the compressed ammonia from the        Compressors (203), which provides heat to the supercritical        ammonia Evaporator (209).

This invention refers also to a procedure for the generation of energybased on a Combined Cycle implemented using the installation definedearlier.

The procedure defined consists of:

-   -   implementing a constituent Brayton cycle, closed or based on        oxy-combustion, regenerated by a heat pump (UAX), which uses        water as thermal fluid and produces mechanical energy in the        high-temperature Turbine TAT (102),        -   implementing a constituent Rankine cycle interconnected with            the foregoing Brayton cycle, and which exchanges matter and            energy with it, as both use water as common thermal fluid,            and produces mechanical energy at the Turbine TAP (122),        -   using a heat pump UAX (200) which exchanges energy with the            constituent Brayton cycle to regenerate it and absorb            mechanical energy in certain compressors (203).

In the procedure of the invention, all the water vapour of the cycle canbe condensed completely in the Element (107) where the CO₂ is releasedin gaseous phase in the case that the Cycle is using fuels other thanhydrogen.

According to particular embodiments of the procedure, the water vapourwhich circulates through the Element (107) condenses completely as aresult of the heat which is transmitted to the cold reservoir of the UAX(200), leaving as residue liquid or gaseous CO₂ only, as applicable, inthe case that the Cycle is using fuels other than hydrogen.

In the procedure according to the invention, the regeneration of theconstituent Brayton cycle can be accomplished by the action of the heatPump UAX (200), recycling the vapour condensation heat at thetemperature of the cold reservoir, to then return it to the cyclethrough the hot reservoir, to regenerate water vapour at higher pressureand temperature than those at which it was previously condensed.

According to particular embodiments, the procedure includes:

-   -   condensing the water vapour at ambient pressure in the Element        (107), relinquishing the heat obtained to the cold reservoir        (201) of the heat pump UAX (200)    -   regenerating water vapour in the Reboiler (113) at a higher        pressure than that at which it was condensed in the Element        (107), using the heat provided by the hot reservoir (210) of the        heat pump UAX (200).

According to particular additional embodiments, the procedure includesthe use of a supplementary heat Source (132), which provides additionalheat to the power Cycle from outside, situated between the Superheater(121) and the Turbine TAP (122).

According to particular additional embodiments, the procedure includesthe use of a single heat sink, through which the Cycle releases lostheat outside. The function of the heat sink can be performed by anindependent secondary Rankine cycle.

According to particular additional embodiments, the procedure includesthe use of a heat recovery Conduit CRC (103), which uses the remainingheat form the outlet of the Turbine TAT (102) to generate superheatedvapour of the constituent basic Rankine cycle.

According to particular additional embodiments, the procedure includesimplementing an oxy-combustion Combined Cycle, and uses liquid orgaseous fuels, of general formula C_(x)H_(y)O_(z) in pure or mixed form,where x, y and z take values corresponding to real chemical compoundscapable of being burned with oxygen. The preferred fuels arehydrocarbons which are gaseous or of low boiling point, such as, forinstance: methane, ethane, propane, or mixtures of these, such aspurified natural gas. Simple alcohols such as methanol or ethanol arealso usable fuels. CO (carbon monoxide) is the only substance free ofhydrogen which is amenable to use as a fuel in the burners of theCombined Power Cycle.

According to particular additional embodiments, the procedure includescondensing part of the water vapour from the heat recovery Conduit (103)using the heat sink and the condensation exchanger (106/110) before theElement (107) finally condenses all the water vapour which is at ambientpressure.

Another part of the condensation heat of the heat exchanger Element(114) can be used to preheat the fuel and the comburent separately usinga heat exchanger Coil (131). This application, of preheating the fueland comburent of the Combined Cycle using the heat obtained in the Coil(131) does not preclude any other kind of additional use to which thisheat could be put, and even if these are applications beyond the scopeof the Power Cycle. When the cycle has a heat exchanger Element (131) topreheat the fuel and comburent of the Combined Cycle, this can, withoutdistinction, be located inside the Element (114), or at the end of theConduit (103) or (105), prior to the entry of vapours and gases into theElement (106).

According to particular additional embodiments, the procedure includesraising the pressure of the vapour provided by the Element (112) and thevapour pressure of the Reboiler (113) and which emerges from thecondensation exchanger Element (114) using the additional mechanicalCompressors (115) and (117), connected in series and capable ofsupplying sufficient pressure to send this vapour to the essential heatSource (101).

One part of the condensate generated in the Element (114) is employed tocool the vapour between the stages of compression circulating throughthe cooling Coil (118) while the rest of the condensate is returneddirectly to the Reboiler (113).

-   -   According to particular additional embodiments, the procedure        includes a bypass that connects the constituent Brayton cycle to        the constituent basic Rankine cycle, with which water is        exchanged, that bypass being located between the impulsion line        of the regeneration condensate Pump (111) and the aspiration of        the feedwater Pump (119).

According to particular additional embodiments, the procedure alsoincludes using the partial condensation heat of the vapour emerging fromthe Reboiler (113) for other applications, in a particular way suitablefor its use in an independent application external to the Installationmaking use of the Coil (131).

According to particular additional embodiments, the procedure includesraising the pressure of the vapour provided by the Reboiler (113) usingthe additional mechanical Compressors (115) and (117), connected incascade, with cooling in-between and capable of supplying sufficientpressure to send this vapour to the essential heat Source (101).

According to particular additional embodiments, it includes:

-   -   in the case that the Combined Power Cycle is implemented as        closed, or burns only hydrogen, to send vapour directly from the        heat recovery Conduit CRC (103) to the Turbine TBP (127) of the        secondary Rankine cycle, which operates under vacuum conditions        provided by the Condenser (128), from where the condensate is        returned as feedwater to the constituent basic Rankine cycle.        With this procedure, the secondary Rankine cycle uses the same        thermal fluid as the rest of the Power Cycle.

According to the procedure of the invention, the outlet gases from theheat recovery Conduit CRC (103) can be compressed using a Fan (104)which sends them to a condensation exchanger Element (105), in whichvapour is generated in an Evaporator (125) of an independent secondaryRankine cycle.

According to the procedure of the invention:

-   -   the heat pump UAX (200) is a refrigerating machine which        functions by combining operations of compression and absorption,        using NH₃ as thermal fluid and water as solvent,    -   the main Generator (201) of the heat pump UAX (200) acts as the        cold reservoir, absorbing the heat from the Element (107),        exclusively,    -   the only cold reservoir of the heat pump UAX (200) works at        temperatures between 80° C. and 120° C.,    -   the ammonia Absorber (210) of the heat pump UAX (200) acts as        the hot reservoir, transferring the heat to the Reboiler (113),        exclusively,    -   in the heat pump UAX (200), the compression of the NH₃ vapour        takes place, in successive stages with cooling in between,    -   the compressed ammonia vapour Condenser (207) of the heat pump        UAX (200) relinquishes all of the heat released by the secondary        Generator (202), and    -   the ammonia Evaporator (209) of the heat pump UAX (200)        generates NH₃ in a supercritical state using the heat    -   supplied to it by the cooling coils between the stages of        compression (204 and 206), and    -   with part of the latent heat held by the concentrated solution        which emerges hot from the Absorber (210).

An essential part of the invention is a Heat Pump of hybridcompression-absorption operation, “UAX” (Absorber unit for exchangingheat) which is capable of fulfilling these requirements efficiently andeconomically to accomplish the regeneration of the constituent Braytoncycle of the Combined Cycle of this invention.

The Absorber unit for exchanging heat UAX (200) is a thermodynamicsystem of mixed functionality, compression and absorption, andwater-ammonia, which works cyclically and continually, which is employedas heat pump to transfer heat energy from a main Generator which desorbsammonia (201) and acts as cold reservoir, to an ammonia

Absorber (210) which works at higher temperature and acts as hotreservoir, making use of a certain amount of mechanical energy providedfrom the outside by a compressor system (203).

The absorption heat pump UAX does not interchange matter with theCombined Power Cycle, but it does receive from it both the mechanicalwork of compression and the heat absorbed by its cold reservoir to,subsequently, restore all this energy to the Cycle by means of its hotreservoir.

The Combined Cycle transfers mechanical energy from the power Shaft(130) to the system of compressors of the UAX and heat energy from anElement (107) to the cold reservoir of the UAX, while the latter returnsto the Combined Cycle all this energy by transferring heat from the hotreservoir to a Reboiler (113) which regenerates water vapour at a highertemperature than that at which it was previously condensed.

From the functional point of view, the heat pump UAX (200) operates athermodynamic cycle which works in “thermodynamic symbiosis” with theCombined Power Cycle to which it is energetically coupled, in such a waythat the functioning of the Installation according to the invention isdetermined by the establishment of this functional link between thePower Cycle and the UAX. This represents a key difference with respectto the combined cycles of the current state of the art.

Essential Components of the Combined Power Cycle

For an installation to function according to the Combined Cycle of theinvention as such, an array of essential equipment is indispensablyrequired, without taking into account its efficiency and ignoring anyother types of factors decisive to the economic viability of aninstallation of this type.

The “essential” components indispensable for an installation to functionaccording to the Combined Cycle of this invention are as follows:

101: Essential heat Source. This is the indispensable focus by whichheat enters the constituent Brayton cycle. The Combined Power Cyclereceives energy from outside, and indispensably, by means of theessential heat Source.

Three currents reach the essential heat Source (101) (in addition to thefuel and comburent in the cases of semi-closed cycles). On the one hand,the vapour from the Turbine TAP (122) of the constituent basic Rankinecycle, and, secondly, the compressed vapour from the constituent Braytoncycle. The final intake current, part of the condensate impelled by thePump (129), which may circulate through the heat exchanger Element (118)before reaching the heat Source (101), in the case that the Power Cyclehas a vapour cooling system between the stages of compression.

The essential heat Source (101) is, therefore one of the points wherecurrents belonging to the constituent Brayton cycle and the constituentbasic Rankine cycle converge, which means that implicitly, this is apoint of interchange of matter between the two constituent cycles.

When the Combined Cycle is working as a closed cycle, the essential heatSource (101) is always a high-temperature heat exchanger that receivesheat energy from outside. In such a case, the only substance thatreaches the essential heat Source (101) is water which, after increasingits enthalpy here, emerges in the form of superheated vapour which issent to the high-temperature Turbine TAT (102).

When the essential heat Source (101) is a pressurised internaloxy-combustion burner, the Combined Cycle is semi-closed. In such acase, the water vapour sent to the high-temperature Turbine (102)circulates accompanied by the gases of the combustion itself (basicallymade up of carbon dioxide and more water vapour).

102: High-temperature Turbine. TAT. This is the gas turbine, basic tothe constituent Brayton cycle, whose function is to generate mechanicalwork with the hot gaseous phase sent to it by the essential heat Source(101). It is referred to as TAT for short (an acronym forHigh-Temperature Turbine in Spanish) because it is the turbine thatworks at the highest temperature in the entire installation.

The gaseous phase moved by the Turbine TAT (102) is made up of steamaccompanied by the combustion gases in the case that the essential heatSource (101) is a burner. This gaseous phase, after being expanded,emerges from the Turbine TAT (102) at high temperature and is sent tothe heat recovery Conduit CRC (103) to harness the enthalpy it contains.

103: Heat recovery Conduit. CRC. This is the gas side of the heatexchanger which recoups the heat from the escape gases from the Turbine(102). This heat held in the turbine gases is employed in the CRC (103)to generate the essential high-pressure vapour for the constituentRankine cycle using the tubular pipe Evaporators and Superheaters (120).Part of the heat contained in the escape gases from the Turbine TAT(102) can be used for external applications beyond the scope of theCycle itself, in what is known as “cogeneration”. Optionally, for thispurpose, and depending on the operational design parameters of theCombined Cycle, in the interior of the CRC (103), there can be someindependent heat exchanger Element (133).

-   -   Moreover, when the medium-pressure Reheater (134), the        Superheater (136), the Superheater (126) and the low-pressure        Evaporator (125) are present, these will always be located        inside this CRC (103). Optionally, the heat exchanger Coil (131)        can be deployed within the CRC (103), situated at the end of        this conduit, prior to the exit of the gases.

Finally, the gases always leave the CRC (103) at the water vapoursaturation temperature corresponding to the “ambient pressure”.

In Configuration-2 (FIG. 2) and in the essential configuration (FIG. 1)of the Combined Cycle presented, the design considers that partialcondensation of the water vapour circulating within the final section ofthe heat recovery Conduit CRC (103) takes place.

Configuration-3 or the design version of the Combined Cycle according toFIG. 3, and Configuration-5 according to FIG. 6, are characterised bythe fact that condensation does not happen in the heat recovery ConduitCRC (103) and a specific Conduit (105) is provided where thecondensation takes place.

For its part, Configuration-4 or the design version of the CombinedCycle according to FIG. 4, is characterised by the fact that thereexists a vapour extraction connection in the CRC (103), just beforecondensation takes place, and by means of which steam is sent directlyto the Turbine TBP (127).

128: Heat Sink In this report, the heat Sink (128) is considered to beany equipment, device or system through which the Power Cycle transmitslost heat to the outside environment. In this invention, this is alwaysa vapour Condenser, a single element through which lost heat energy iscarried to the exterior. Nevertheless, this function is indispensablefor the functioning of the constituent basic Rankine cycle, for theInstallation of the invention as a whole. Any heat exchanger elementwhich condenses water vapour contained in the outlet gases from the CRC(103) can perform the function of a heat Sink (128); nevertheless, andfor reasons of energy efficiency, the most economical solution consistsof providing some system which recovers that heat (which is capable ofproducing the condensation of water vapour at ambient pressure on theother side of the heat exchanger), such as, for instance, an evaporatorbelonging to another additional Rankine cycle or a coil which extractsheat intended for any type of application of interest (perhaps, forexample, a heat recovery system coupled to an absorption machine toproduce industrial cold). When the Combined Cycle has a secondaryRankine cycle, its Condenser (128) is always the equipment by which heatis transmitted to outside.

109: Condensate return Pump to the constituent basic Rankine cycle. Thisis the pump which displaces the condensate produced by the heat Sink(128) and makes it circulate through a condensate return Preheater (110)before distributing the water which feeds different parts of the cycle.

110: Feedwater preheater Element. This comprises a heat exchangertogether with the Element (106) within which it is located. This is atubular coil or heat exchanger element of any other configuration whosemission is to raise the temperature of the condensate it returns to thecycle impelled by the Pump (109), using the heat from the vapourcondensation that takes place on the shell side of the exchanger (106).

106: Shell side of the condensation exchanger of the feedwaterpreheater. This comprises a heat exchanger together with the condensatereturn preheater Element (110). This is the element of the exchangerthrough which the remaining vapour obtained from the bottom of the CRC(103) circulates, accompanied by the incondensable gases in the case ofan oxy-combustion cycle. In the element (106), partial condensation ofthe water vapour takes place. With the heat released in thiscondensation, the temperature of the return condensate is raised, makinguse of the condensate return Preheater (110). Emerging from thiscondensation heat exchanger Element (106), to be directed to the Element(107), is the current of water vapour accompanied by all theincondensable gases, when there are any, produced in combustion (whenthe cycle is closed there are no burners and when the fuel is hydrogenwith pure oxygen, no incondensable gases are produced in thecombustion).

In the bottom of the heat exchanger Element (106), liquid water isobtained from the condensation which is then impelled by theregeneration condensate Pump (111) together with the condensate currentfrom the Element (107).

107: Regeneration condenser or liquefaction plant. The Element (107)transfers all the heat from the condensation of the vapour to the mainGenerator (201) which acts as “cold reservoir” of the heat pump UAX(200).

The regeneration Condenser (107) receives the vapour and incondensablegases from the Element (106). In turn, from (107), the incondensablegases are obtained on one side, and the condensed water vapour on theother side. The regeneration Condenser (107) works at “ambient pressure”which corresponds to working at the lowest temperature of theconstituent Brayton cycle. The simplest option, although this is notindispensable, is to make the regeneration Condenser (107), just likethe heat exchanger Element (106) and the outlet from the CRC (103),operate at pressures close to atmospheric, in which case thecondensation temperatures in these three components will be close to100° C.

-   -   Although it entails a reduction in the overall performance, a        feasible option, more complex but of greater relevance from the        point of view of the interest in the industry in semi-closed        cycle configurations, consists of making the Element (107) a CO₂        liquefaction plant, in which all the heat released in the        successive cycles of compression is transmitted to the Generator        (201) of the UAX (200). The objective of this configuration is        to extract the liquefied oxy-combustion CO2 from the Power Cycle        for storage, transport and handling, instead of taking it out in        a gaseous state.    -   The condition demanded of the Element (107) for it to be a CO₂        liquefaction plant is that the heat generated in the different        stages of compression is at a sufficient temperature to be        transmitted from the cooling exchangers between the CO₂        compression stages, to the main Generator (201) of the UAX.    -   In this case, it should be considered that the mechanical work        of the compressors is supplied by the power Shaft (130) itself        of the Installation (for reasons of simplicity this        representation has been omitted in all the figures attached).

This heat that the power Cycle relinquishes to the UAX (200) is returnedlater at a higher temperature by means of the Reboiler (113), whichworks with the heat provided to it by the ammonia Absorber (210) thatacts as the “hot reservoir” of the UAX (200) Without regard to whetherthe Combined Cycle is working in a closed or semi-closed cycle, in theElement (107), complete condensation of the water vapour arriving therefrom the Element (106) always takes place. As a consequence of thisoperation, the water vapour turns to liquid while the CO₂ generated inthe combustion remains confined in concentrated gaseous or liquid phase.

Among other things, this means that the CO₂ which emerges from the cycledoes so at very much lower temperatures with respect to otherconventional combined cycles. This CO₂ exit temperature can be reducedeven more if, for example, some other additional heat exchanger for thecondensate return current of the Combined Cycle is provided.

This separation of phases which takes place in the Element (107) meansthat all the CO₂ generated in burners and any other incondensablegaseous waste that may accompany it, can be eliminated from the cycle,with no need for it to come into contact with the atmosphere.

This confers an important environmental advantage upon the power Cycleof this invention over conventional open combined cycles, because itdoes not entail the direct emission into the atmosphere of any type ofenvironmentally polluting gases.

It is common in oxy-combustion processes to burn with about 2 or 3%excess oxygen over the stoichiometric value to ensure completecombustion. This amount of oxygen which has not reacted circulates fromthe burners passing through the CRC (103) and the heat exchanger Element(106), diluted in the thermal fluid, until it finally reaches theElement (107), where it is eliminated from the cycle as an incondensablegas together with the CO₂. When this happens, the excess oxygen used forthe combustion can be recovered in the carbonic anhydride treatmentplant to be reused as comburent for the Cycle.

Finally, in the bottom of the Element (10 t), degassed water is obtainedwhich is returned to different part of the Combined Cycle impelled bythe regeneration condensate Pump (111). Therefore, the only section ofthe Power Cycle which may contain CO₂ is that from the burners (101) and(122) to the Element (107).

113: Regeneration Reboiler of the constituent Brayton cycle. This is theregenerator element of the constituent Brayton cycle by which the “heatpump” UAX returns to the Combined Cycle, in the form of heat, the amountof energy previously recouped from the Cycle itself using the Element(107) as well as the amount of energy the Compressors (203) of the UAXtake from the power Shaft (130).

The Reboiler (113) is the heat exchanger element by means of which heatis returned to the Power Cycle from the ammonia Absorber (210), whichacts as “hot reservoir” of the UAX (200). With this heat supplied by theUAX (200) by means of the Absorber (210), the Reboiler (113) regenerateswater vapour at a temperature and pressure above those at which itpreviously condensed in the Element (107).

Therefore, the regeneration of the constituent Brayton cycle using theheat pump UAX (200) takes place by recycling the vapour condensationheat at the temperature of the “cold reservoir” to subsequently returnit to the cycle, using the “hot reservoir”, to regenerate water vapourat a temperature and pressure above those at which it previouslycondensed.

111: Regeneration condensate Pump of the constituent Brayton cycle. ThePump (111) aspirates the condensate generated in the condensation heatexchanger Element (106) together with the degassed water obtained in thebottom of the Element (107) and impels it to the Element (112) atsufficient pressure for it to, finally, feed the Reboiler (113).

In the impulsion line of this regeneration condensate Pump (111), abypass is provided with the aspiration line of the feedwater Pump (119),by means of which water is exchanged between the constituent Brayton andRankine cycles to establish the balance of matter and energy which isindispensably required to enable constitution of the Combined Cycleaccording to this invention, and which depends on the design variablesof the installation and the conditions of operation of the cycle.

112: Element (112), selected from:

-   -   a Preheater (112) for the intake water to the Reboiler itself        (113)    -   and a heat recovery exchanger (112), which in addition to        preheating the intake water for the Reboiler (113) itself, can        heat the feedwater to the Pump (119) and generate vapour which        can be directed to the compressor (115) and/or a turbine a        heater (137) once its temperature has been raised in a        Superheater (136)

The Element (112) is a tubular coil or heat exchanger element of anyother configuration which is inside a condensation heat exchangerelement (114) from which it receives heat, raising the temperature ofthe water that feeds the regeneration Reboiler (113).

What enters the Element (112) is the condensed water from the pumps(109) and (111). What leaves the heat exchanger Element (112) is

-   -   a current of heated liquid water which is sent to the Reboiler        (113), and if it performs solely this function it is termed        Preheater (112).

In addition, two further currents may emerge from the Element (112):

-   -   A current of heated liquid water which is sent to the feedwater        Pump (119).    -   A current of steam (at pressure above atmospheric) which is sent        to the first additional stage of the vapour Compressor (115)        or/and the Superheater (136) to then expand partially inside the        additional Turbine (137) before it enters the Turbine TBP (127).

114: Shell side of the condensation exchanger of the Element (112). Thisis a condensation heat exchanger element inside which is found the-Element (112). The vapour from the regeneration Reboiler (113)circulates through the present Element (114), where the water vapourcondenses partially, entailing that the enthalpy is recovered in theElement (112) which in addition to preheating the water feeding theReboiler (113) itself can heat the feedwater for the Pump (119) or/andgenerate vapour. As a result of the partial condensation that takesplace, a current of liquid water is obtained from the bottom of theElement (114). This condensed water is impelled using a condensate Pump(129) and part of it is sent to the essential heat Source (101), passingpreviously through a heat exchanger Element (118) that cools the vapourbetween the stages of mechanical compression (115) and (117). The otherpart of the condensate impelled by the condensate Pump (129) isrecirculated directly to the Reboiler (113). In the case that theCombined Cycle does not have the supplementary vapour Compressors (115)and (117), part of the condensate impelled by the Pump (129) can be sentdirectly to the essential heat Source (101).

Optionally, and with a view to improving the performance of the Cycle,it is also possible to provide an additional Coil (131) inside theElement (114) which, among other applications, could be employed topreheat the fuel and the comburent from the conditions of their supply.This Coil (131) could also, without distinction, be located immediatelybefore the vapour and gases enter the Element (106). This Coil (131) canalso be used to extract heat from the Element (114) intended for othertypes of external applications beyond the Installation itself.

129: Bottom condensate Pump of the condensation Exchanger (114). This isthe pump that impels the condensate obtained from the bottom of theElement (114) at a pressure sufficient for sending to the essential heatSource (101). When the Combined Cycle has Compressors (115) and (117),this current of water impelled by the condensate Pump (129) circulatesthrough the Coil (118) to cool the vapour between the two stages ofcompression. After the condensate Pump (129), this current is divided intwo. One part is sent to the essential heat Source (101), passingpreviously through the heat exchanger Element (118) in the case that theCombined Cycle has a Compressor (115), while the remaining part of thecondensate impelled by the Pump (129) is returned directly to theReboiler (113).

119. Feedwater Pump for the constituent basic Rankine cycle. This is thepump that impels water through the vapour generator elements of thebasic Rankine cycle. This pump provides the highest pressure valueyielded in the entire installation.

The feedwater Pump (119) is fed fundamentally by the return current ofthe condensate impelled by the Pump (109). In addition, the CombinedCycle has a bypass, between the impulsion of the Pump (111) and theaspiration of the Pump (119), through which it is possible to exchangethermal fluid (water) between the constituent Brayton cycle and theconstituent basic Rankine cycle. There exists the possibility of alsosupplying the feedwater Pump (119) with a current of water heated in theElement (112). The direction of flow in this bypass is determined by thedesign and cycle operation variables.

120: Economisers or Economiser tubular Pipes of the constituent basicRankine cycle. These are the heat exchanger elements located inside theCRC (103) which serve to preheat the supply water from the feedwaterpump (119) to a temperature close to that of its boiling point, with thepressure at which vapour is generated in the constituent basic Rankinecycle.

121: Tubular pipes of the Evaporator and Superheater of the constituentbasic Rankine cycle. The Evaporators and Superheaters are the heatexchanger elements located inside the CRC (103) which generate thepressurised vapour of the constituent basic Rankine cycle The waterpreheated in the Economisers (120) enters the evaporator pipes, andfinally superheated water emerges which is sent to the Turbine TAP (122)or to the supplementary heat Source (132) in the event that the PowerCycle incorporates this element.

122: (High-pressure) Turbine of the constituent basic Rankine cycle TAP.The purpose of this vapour turbine is to generate work according to theconstituent basic Rankine cycle. The Turbine TAP (122) receivessuperheated steam from the tubular pipes of the last Superheater (121)or the supplementary heat Source (132) if this is available. It is thecharacterised by being the turbine that works at the highest pressure inthe entire installation, so that it is referred to as TAP for short (anacronym for High-Pressure Turbine in Spanish). This turbine works atback pressure, carrying out a partial expansion of the gaseous fluid insuch a way that the outlet vapour is at sufficient pressure to reach theessential heat Source (101) to which the escape vapour is sent.

When, although this is inessential, the Power Cycle has a Turbine TPI(135), this receives vapour from the escape or extracted from theTurbine TAP (122).

130: Power Shaft of the installation. This is the element or array ofelements to which all the machines of the installation requiring orgenerating mechanical work (turbines, pumps and compressors) arecoupled. This power Shaft represents the point from which the usefulmechanical energy of the installation (to which the turbines,compressors and pumps of the installation are coupled) is obtained.

With the exception of the pumps and Fan (104), a common power Shaft(130) is represented in the attached figures to facilitate comprehensionof how the net mechanical Combined Cycle is obtained, although it isalso feasible to embody any Power Cycle according to this inventionemploying individual power shafts connected to independent generators ormotors.

Fundamental Components of the Heat Pump (UAX)

The UAX, as has been indicated, is an essential component of theinstallation of the invention which works with ammonia and water.

The components comprising the heat pump UAX are shown in FIG. 5 of thedrawings. The equipment making up a UAX is:

201: Main Generator. This is an ammonia desorber which acts as the “coldreservoir” of the UAX and is responsible for receiving the heat releasedby the Element (107) belonging to the Combined Power Cycle. The mainGenerator is fed by the intermediate concentration solution ofammonia-water from a secondary Generator (202), and on one side humidgaseous ammonia emerges for compression, while on the other side thedilute solution which is sucked in by a transfer Pump (215) comes out.

202: Secondary Generator. This is a partial ammonia desorber which worksusing the heat supplied to it by a compressed ammonia vapour Condenser(207). The entire concentrated solution produced at an ammonia Absorber(210), after having been previously cooled, enters the secondaryGenerator. What emerges from the secondary Generator is, on one side,humid gaseous ammonia to be compressed together with the ammoniaobtained from the main Generator (201) and, on the other side, thepartially degassed water obtained from the bottom, to be sent to feedthe main Generator (201). The secondary Generator (202) works at apressure slightly higher than the main Generator (201) to get thesolution to flow from one of these to the other.

203: Ammonia Compressors. This term is applied to the array ofcompressors connected in series whose function is to raise the pressureof the humid gaseous ammonia from the two Generators (201) and (202).Compression of the gaseous ammonia is conducted in successive stages ofcompression connected in series with intervening cooling of the gas,with the aim of maximising the overall efficiency of the process. Toachieve this, the compressor array receives mechanical work from thepower Shaft (130) of the Combined Cycle installation. The array ofCompressors (203) raises the pressure of the gaseous ammonia to, atleast, enable the NH₃ saturation temperature to exceed the temperatureat which the secondary Generator (202) carries out desorption so thattransmitting the heat to this latter equipment is possible.

This refrigerant gas compression stage does not take place inconventional absorption machines, so that this is an essentialcharacteristic of the UAX. By making use of an absorption-desorptioncycle in addition to compressors, it is considered that the UAX (200) isa hybrid absorption and compression system that, taken as a whole, actsas a heat pump.

The compressed ammonia vapour which emerges from the last stage is madeto circulate through a final compressed ammonia cooling Element (205),and immediately another cooling Coil (206), which means that the heatcontained in this compressed vapour is reused in other elements of theUAX.

204: Gaseous ammonia cooling Elements between the successive stages ofcompression. This is made up of all the heat exchanger elementsresponsible for cooling the gaseous ammonia between each pair of stagesmaking up the Compressor (203). All these heat exchanger elements aresituated inside a supercritical ammonia Evaporator (209), to which theyrelinquish all the heat they give off, for which reason the temperatureof operation of each of these cooling Elements (204) has to exceed theoperational temperature of the supercritical ammonia Evaporator (209).

205: Final compressed ammonia cooling Element. Taken together with thefinal dilute solution heater Element (216), this comprises a heatexchanger. What circulates through the final compressed ammonia coolingElement (205) is the vapour that emerges from the final stage of theCompressors (203), relinquishing heat to the final heater Element (216)with the object that the dilute solution should reach the ammoniaAbsorber (210) at a temperature no lower than that at which absorptionof the gas in this Element (210) takes place. In view of this fact, thisElement (205) is the one that has the highest temperature in the entireUAX (200).

206: Compressed ammonia cooling Coil. This lies inside the supercriticalammonia Evaporator (209), downstream from the final compressed ammoniacooling Element (205). In this Coil (206), the compressed gaseousammonia is cooled before it reaches the compressed ammonia vapourCondenser (207). The heat released by the Coil (206) is used internallyto generate gaseous ammonia in the ammonia Evaporator (209), so that itworks at a temperature above (that of) the critical point of NH₃.

207: Compressed ammonia vapour Condenser. In this equipment, thesaturated ammonia vapour under pressure supplied by the Compressors(203) is converted into the liquid phase and transmits all the heat,which it releases by condensation, to the secondary Generator (202) sothe latter can carry out desorption.. The compressed ammonia vapourCondenser (207) receives the ammonia in gaseous state from the exchangerElement (206) at the lowest temperature possible, although in such a waythat the secondary Generator (202) can function properly. The Expander(218) is what separates the Coil (206) from the Condenser (207).

The liquid ammonia obtained from the compressed ammonia vapour Condenser(207) is impelled to the supercritical ammonia Evaporator ((209) using acondensed ammonia Pump (208).

208: Condensed ammonia Pump. This is the Pump that impels the condensedammonia, with an outlet pressure above its critical point, from thecompressed ammonia vapour Condenser (207) to a supercritical ammoniaEvaporator (209). In the impulsion line of the Pump (208), the highestpressure in the entire UAX (200) is reached.

209: Supercritical pressure ammonia Evaporator. This receives theammonia condensate impelled by the condensed ammonia Pump (208) andconverts it into a gas at a temperature and pressure above the criticalpoint of ammonia (113.5 bar/133.5° C.). To achieve this, the Evaporator(209) reuses the residual heat received, on the one hand, from thecompressed ammonia cooling Coil (206) and the cooling Elements (204),which transmit the heat that has been generated by the Joule-Thomsoneffect in the Compressors (203). On the other hand, it also reuses thelatent heat transmitted to it by a concentrated solution Coil (211)(more concentrated than the solution that comes out of the desorber),through which one part of the concentrated solution emerging from theAbsorber (210) circulates. This implies that the supercritical ammoniaEvaporator (209) performs its function by using recycled heat from theUAX system itself, with no contribution from other external sources ofheat being required.

The gas that emerges from the ammonia Evaporator (209) in asupercritical state is carried immediately to the Absorber (210).

210: Ammonia Absorber. The purpose of this is to dissolve the gaseousammonia in water under conditions of supercritical pressure andtemperature. This is the element that acts as the “hot reservoir” of theUAX and which is responsible for transmitting the heat it gives off tothe regenerator Reboiler (113) of the Combined Power Cycle.

The Absorber (210) is fed by the gaseous ammonia from the supercriticalammonia Evaporator (209), making use of the Expander (217), and,moreover, it is also fed by the dilute ammonia-water solution from themain Generator (201) after having been impelled by the transfer Pump(215) and preheated by the heat exchanger Elements (214) and (216),successively.

Emerging from the Absorber (210) is the concentrated ammonia solutionthat is sent to the secondary (202) and main (201) Generators, thusclosing the absorption-desorption cycle. Following its emergence fromthe Absorber (210), the flow of concentrated solution is divided intotwo currents. One part is made to circulate through the heat exchangerElement (213) of the counterflow exchanger, while the remaining flowcirculates through the concentrated solution Coil (211) which providesheat with which supercritical ammonia is generated in the Evaporator(209). Finally, having exchanged their heat, the two solutions ofconcentrated solution are united again before the Expander element(212).

The dissolution of ammonia in water under supercritical conditions is anexothermic process. The heat released by the ammonia Absorber (210) istransferred to the Reboiler (113) to regenerate vapour in the CombinedPower Cycle. Thus, the Absorber (210) discharges the function of “hotreservoir” of the UAX (200).

211: Concentrated solution Coil in the Evaporator (209). This is foundinside the supercritical ammonia Evaporator (209), where it releasesheat at the cost of lowering the temperature of the concentratedsolution circulating through this Coil (211) from the ammonia Absorber(210).

213: Heat exchanger Element between the dilute and concentratedsolutions. Concentrated solution side. This Element (213) forms part ofa counterflow heat exchanger together with the heat exchanger Element(214). to which it transfers heat. Through this Element (213) circulatesthe complementary part of the concentrated solution that emerges fromthe ammonia Absorber (210)_but does not circulate through theconcentrated solution Coil (211). The mission of this exchanger Element(213) is to lower the temperature of the concentrated solution before itenters the secondary Generator (202).

212: Concentrated solution Expander. Once the two currents ofconcentrated solution which have been cooled in the heat exchangerElements (211) and (213), respectively, have been reunited, the Expander(212), situated just before this concentrated solution enters thesecondary Generator, procures that the operational pressure ofdesorption in the secondary Generator (202) is attained.

214: Heat exchanger Element between the dilute and concentratedsolutions. Dilute solution side: This Element (214) forms part of acounterflow heat exchanger together with the Element (213). from whichit receives heat. The mission of this counterflow heat exchanger is tomake the concentrated solution enter the secondary Generator (202) atthe lowest temperature possible, while at the same time managing to heatthe dilute solution prior to its entry into the ammonia Absorber (210).

Circulating through this heat exchanger Element (214) is the dilutesolution from the main Generator (201) impelled by a transfer Pump (215)before it reaches the Absorber (210), with the objective of heating itin counterflow with part of the concentrated solution.

215: Dilute solution transfer Pump. This is the pump that displaces thedilute solution leaving the main Generator (201) and sends it to theammonia Absorber (210), but passing previously through the heatexchanger Elements (214) and (216) whose purpose is to raise itstemperature.

216: Final dilute solution heater Element. The heat exchanger Element(216) constitutes a counterflow heat exchanger together with the finalcompressed ammonia cooling Element (205). Circulating through thiselement is the dilute solution from the heat exchanger Element (214),and it uses the heat transmitted by the vapour that emerges from thefinal stage of Compressors (203) to ensure that the solution reaches theammonia Absorber (210) at the same operational temperature.

217: Gaseous ammonia Expander towards the Absorber (210). The Expander(217) serves to match the pressure of the supercritical ammonia from theEvaporator (209) to the operating pressure of the ammonia Absorber(210).

218: Gaseous ammonia Expander towards the compressed ammonia Condenser(207). The ammonia Expander element (218) generates the fall in pressureand temperature necessary for the operation of the compressed ammoniavapour Condenser (207) in such a way that the exchange of heat betweenthe Condenser (207) and the secondary Generator (202) can beestablished.

The particular characteristics of the Absorber unit for exchanging heat(UAX) are determined by the operational requirements and variables ofthe Combined Cycle which it is assisting.

To “regenerate” efficiently the constituent Brayton cycle of thisinvention, the heat pump UAX (200) must meet the following conditions:

-   -   Exchange energy solely with the Power Cycle being assisted. That        is, all the heat absorbed by the cold reservoir should be taken        from the Power Cycle and all the heat released by the hot        reservoir should be transferred, anew, to the Power Cycle at a        different point. Exchanging energy with the outside would        represent a loss of efficiency;    -   The cold reservoir of the UAX must capture, for the purposes of        recovery, the water vapour condensation heat at ambient pressure        (between 80° C. and 120° C.).    -   It is required to attain as great a thermal step (temperature        difference) between the reservoirs of the UAX as possible, as        the hot reservoir must regenerate condensed saturated water        vapour in advance, but at the highest pressure possible to        enhance the efficiency of the system;    -   The performance (CoP) should be as high as possible: in other        words, the number of calories transferred from the cold        reservoir to the hot one should be very large in comparison with        the mechanical work consumed by the compressor;    -   All of the energy (mechanical and thermal) that the heat pump        UAX takes from outside must be supplied by the power Shaft (130)        of the very Combined Cycle being assisted;    -   The entirety of the thermal energy (except for the real losses        of the UAX itself) that the heat pump UAX releases should emerge        by means of its “hot reservoir”, and be used to regenerate        vapour in the Power Cycle through its Reboiler (113).

Every absorption machine, and therefore also the UAX, works according toa cyclic process of absorption-desorption. Absorption is the name givento the process of dissolution of a gas in a liquid solvent. The inverse,reversible process under which the gas is released from the solution isknown as desorption. In the specific case of the UAX, ammonia is used asthe solute and water as the solvent.

The absorption of ammonia in water is a reversible exothermic process,so that in every Absorber, there is a release of heat when the gas isdissolved into the liquid phase. For its part, the reverse process ofdesorption of ammonia in water that takes place in the Generator turnsout always to be endothermic, meaning that it needs a supply of heat forit to function.

It is considered that the UAX is a hybrid compression-absorption heatpump as its functioning shares common characteristics with both systems.This means that the UAX is necessarily comprised of absorber, desorber,evaporator, condenser and compressors, in addition to pumps, gasexpander elements and heat exchangers.

Conventional absorption machines are systems consisting of two foci bywhich the machine absorbs heat from outside (generator and evaporator)and another two by which the machine releases heat to the outside(absorber and condenser).

Nevertheless, for a “heat pump” to be useful in regenerating theCombined Cycle of this invention, it is absolutely necessary that itconsist of only one “cold reservoir” (from which it receiveslow-temperature heat from the Power Cycle) and only one “hot reservoir”(by which the heat is returned to the cycle but at a highertemperature). This is precisely the fundamental characteristic of theUAX that distinguishes it from other absorption machines.

Although the UAX (200) consists of the same fundamental elements as anyother absorption machines, it is characterised by absorbing externalheat at only one focus and releasing it by only one other (consideringthat real losses can be neglected). This is achieved by recycling theheat released by some of its elements and reusing internal heat toprovide the heat required by others of its elements.

Due to the physico-chemical affinity displayed by the components of asolution, the process of dissolution of a gas in a liquid always turnsout to be more exothermic than its mere condensation. A directconsequence of this is, in an absorption machine, the foci that work byabsorption-desorption—Absorber (210) and main Generator (201)-releaseand absorb, respectively, more heat than that released in the compressedammonia vapour Condenser (207) and absorbed in the supercritical ammoniaEvaporator (209).

To successfully transfer the maximum specific quantity of heat from itscold reservoir to its hot reservoir, the UAX reuses internally certainflows of heat to prevent its compressed ammonia vapour Condenser (207)and its supercritical ammonia Evaporator (209) from exchanging energywith the outside, so as to maintain the Absorber (210) and the mainGenerator (201) as the sole hot and cold reservoirs, respectively.

From the thermodynamic point of view, and unlike compressionrefrigerating machines, conventional absorption machines cannot strictlybe considered heat pumps, because they do not transport heat from thecooler reservoir to the warmer one. Normally the machine absorbs heatsimultaneously through the coldest element (the Evaporator) and thehottest (the Generator).

One particularity of the UAX (200) distinguishing it from the otherconventional absorption machines is that it really does work as a heatpump, transferring heat energy from a cold point to a warmer one. Thisis achieved by making the heat pump UAX work with its operatingpressures reversed with respect to how refrigerating machines commonlywork.

In any refrigerating machine, whether based on compression orabsorption, there exists one part of the circuit that works at highpressure and another working at low pressure (the condenser works athigher pressure than the evaporator).

In the case of a compression heat machine, the difference in pressurebetween the evaporator and the condenser is forced by a compressor. Thezones of different pressure are demarcated between the compressor andthe expander.

In absorption machines, the generator and the condenser work at higherpressures than the evaporator and the absorber. it is the functioning ofthe absorber-desorber system itself which induces the pressuredifference existing between some components and others.

One specific characteristic of the UAX is that it works with operatingpressures reversed with respect to conventional refrigerating machines:in other words, its Absorber (210) and supercritical ammonia Evaporator(209) function at higher pressure than its compressed ammonia vapourCondenser (207) and its main (201) and secondary (202) Generators. Toachieve this, the transfer Pump (215) makes the dilute solutioncirculate from the Generator (201) to the ammonia Absorber (210), thatworks at a higher pressure.

To work with pressures inverted, the UAX (200) needs mechanical means.On this point, the UAX is distinguished from any other conventionalabsorption machine in that the pressure differential in the circuit isnot induced, but forced, by employing compressors and pumps for thispurpose.

To make the UAX work with inverted pressures, the operationaltemperatures of the Absorber (210) and the main Generator (201) must bedetermined precisely, as two countervailing effects which affect thesolubility of the ammonia in water are produced simultaneously. On theone hand, the liquid phase must be capable of dissolving more gas athigher pressures, but on the other, the gas will turn out to be lesssoluble at higher temperatures.

Obviously, for the system to be able to work as a heat pump it isrequired that the solubility of the ammonia in water always be higher inthe Absorber (210) than in the main (201) and secondary (202)Generators, as in any absorber, there is always a rise in theconcentration as the gas is dissolved, whereas in any generator, adilute solution is always yielded because it is here that desorption ofthe gas takes place.

To reach the maximum efficiency it is necessary to find the idealtradeoff between the operational temperatures and pressures in each casebecause, on the one hand, desorption is fomented in the main (201) andsecondary (202) Generators by lowering the pressure, while the efficacyof the ammonia Absorber (210) rises with its operational pressure.However, bearing in mind that the mission of the UAX is to act as a heatpump, it is intended that the thermal step between the hot and coldreservoirs should be as large as possible. Given this, as thetemperature rises in the Absorber (210), the ammonia tends to becomemore insoluble, while as the temperature falls in the main (201) andsecondary (202) Generators, the solubility tends to rise, hindering theperformance of the desorption.

A thermodynamic system that can transfer heat from a point at lowtemperature to another warmer one using a compressor is known as a “heatpump”, and this is precisely the function discharged by the “Absorberunit for exchanging heat” which is the object of this invention.

In view of the foregoing, it should be pointed out that to get the“Absorber unit for exchanging heat” (UAX) to work as a heat pumpassisting the Power Cycle of the invention it is necessary to carry outa series of specific modifications, which constitute particularcharacteristics of the UAX (200). These specific modifications thatdistinguish the UAX from other absorption cycles are:

-   -   1.—To get the ammonia Absorber (210) to give off heat, but at a        higher temperature than that at which the main Generator works        (201), it is necessary to invert the pressures of operation: in        other words, the Absorber (210) should work at higher pressure        than the component with which ammonia is desorbed, the main        Generator (201). To achieve this, a transfer Pump (215) is        needed, which impels the dilute solution to the ammonia Absorber        (210) and an Expander (212) element for the concentrated        solution before it enters the secondary Generator (202).    -   2.—For the UAX not to lose heat to the outside, it is necessary        to recycle the heat the compressed ammonia vapour Condenser        (207) releases, transferring it to the secondary Generator (202)        desorber, so that the working temperature of the former must be        slightly higher than the temperature of the latter. It is        necessary to raise the vapour pressure of the ammonia using the        Compressors (203), for it to condense at a higher temperature        than that at which it evaporates in the solution in the        generator.    -   3.—Bearing in mind that the heat released by the compressed        ammonia vapour Condenser (207) is recycled in the UAX itself,        the ammonia Absorber (210) constitutes the only point through        which heat is released to the outside (if the real losses of        heat from conduction, convection and radiation are considered        negligible).    -   4.—To raise efficiency, the compression of the ammonia employed        as refrigerant gas is undertaken in several stages with        intervening cooling. This implies that between the stages of        compression, there is an amount of heat that must be eliminated.        Moreover, it is of interest for the compressed ammonia vapour to        reach the compressed ammonia vapour Condenser (207) at the        lowest temperature possible, always provided it can still        transmit heat to the secondary Generator (202).

Making appropriate selections of the operational temperatures of thesystem it is possible to provide the heat the Evaporator (208) needs, bytransferring to it the excess heat contained in the vapour current afterthe Compressors (203) and the concentrated solution that emerges fromthe Absorber (210), to convert the ammonia to a supercritical state.When the sum of these excess heats satisfies the demand of the ammoniaEvaporator (209), it becomes unnecessary to furnish heat from outside toproduce ammonia in conditions beyond its “critical point”, and at thesame time the need to evacuate cooling heat to the outside vanishes.

-   -   5.—By supplying the heat the supercritical ammonia Evaporator        (209) needs with heat recycled from the system itself, the main        Generator (201) becomes the only focus by which the UAX receives        heat from the outside.

Undertaking all these modifications appropriately, it turns out to befeasible to design an absorption machines which, by making use of anarray of Compressors connected in cascade (203), prevents its compressedammonia vapour Condenser (207) and its supercritical ammonia Evaporator(209) from exchanging heat with the outside, leaving the main Generator(201) as the only cold reservoir by which the system absorbs heat fromthe outside, while the Absorber (210) works at a higher temperature,acting as the only hot reservoir by which heat is released to theoutside.

Functioning of the Heat Pump (UAX)

-   -   1.—In order that the UAX (200), just like any other absorption        system, can operate continuously in a closed cycle, it is        necessary to establish a circuit for interchanging solutions        between a component that “absorbs” the gas, producing the        concentrated solution, and another that “desorbs”, yielding the        dilute solution. In other words, the dilute solution emerges        from the main Generator (201) and circulates to the ammonia        Absorber (210), while the concentrated solution leaves the        Absorber (210) and circulates to the main Generator (201) in the        opposite direction, to be recycled afresh.

According to the foregoing, a counterflow circulation is established forthe two solutions between one piece of equipment and another (Absorber(210) and Generator (201), but in the opposite direction.

Given that the generators (desorbers) and absorbers of an absorptionmachine always work at different pressures, the solution flows form themachine at higher pressure toward the one at lower pressure with no needfor mechanical assistance. However, the other solution circulating incounterflow from the equipment at lower pressure toward the one athigher pressure needs to be driven by a pump.

In the UAX (200), unlike conventional absorption machines, the Absorber(210) works at a higher pressure than the main Generator (201) and, inconsequence, the transfer Pump (215) impels the dilute solution from themain Generator (201) to the Absorber (210).

10

-   -   2.—The UAX (200) consists of two desorbers or generators, one        which we call secondary Generator (202) and the other the main        Generator (201). The two generators work in cascade, meaning        that the partially desorbed solution emerging from the secondary        Generator (202) constitutes the supply for the main Generator        (201).

Desorption of the ammonia requires the addition of heat, as this is anendothermic process, so that all the generators require the supply ofheat to function. In the UAX, each Generator receives heat from adifferent source: The secondary Generator (202) is supplied with heat bythe compressed ammonia vapour Condenser (207), while the main Generator(201) receives heat from the Combined Cycle. As a consequence, theworking temperature of the main Generator (201) is always determined bythe condensation temperature of the fluid in the constituent Braytoncycle. This condensation takes place in the Element (107).

The operating pressure of the Generators (201) and (202) of the UAX(200) depends on the degree of desorption (concentration of the dilutesolution) for which the UAX is designed, although the secondaryGenerator (202) always works at a pressure significantly higher than themain Generator (201) so that the intermediate concentration solutionflows from one of these to the other without the need for mechanicalmeans.

The main Generator (201) is the equipment that works at the lowestpressure in the UAX (200) and therefore it is required that the dilutesolution obtained from this component circulates impelled by thetransfer Pump (215) at pressure sufficient to feed the ammonia Absorber(210).

-   -   3. The ammonia vapour obtained from the two Generators, the main        (201) and the secondary (202), just like that obtained in any        conventional desorber, always contains a certain amount of        humidity. In this patent, the term “ammonia vapour” in the UAX        (200) always refers to a “humid” ammonia vapour unless otherwise        indicated. In this report, no special consideration is afforded        to this humid ammonia as this degree of humidity is very low        under the pressure and temperature conditions demanded of the        UAX, and this does not alter the essential functioning of the        cycle.

This ammonia desorbed in the Generators (201 and 202) is sent to thearray of Compressors (203). Here, the process of compression is carriedout in successive stages with intervening cooling of the fluid which isbeing compressed, for the twin purposes of improving the mechanicalefficiency of the compression, on the one hand, and on the other, tohave several thermal reservoirs capable of providing heat to thesupercritical ammonia Evaporator (209). That is to say, the set ofcooling Elements (204) between the stages of compression, transfers thisheat to the ammonia Evaporator (209), thus averting its loss outside thecycle.

The set of Compressors (203) obtains its mechanical work from theCombined Cycle itself by means of the power Shaft (130), so that thiswork is considered as self-consumption by the Combined Power Cycle.Given that the lower the self-consumption of mechanical energy, thegreater the net efficiency of the Combined Cycle, it is of interest forthe process of compression to be as efficient as possible.

The final pressure of the vapour emerging from the final stage of theCompressors (203) is determined by the operational pressure of thecompressed ammonia vapour Condenser (207), and this in turn is a directfunction of the temperature at which desorption takes place in thesecondary Generator (202) with which it exchanges heat.

-   -   4.—It is an operational requirement of the UAX that the ammonia        vapour has to come out of the last stage of Compressors (203) at        a temperature higher than that of the Absorber (210), so that        the final compressed ammonia cooling Element (205) can heat the        dilute solution to ensure that the liquid phase enters the        Absorber (210) at a temperature no lower than that at which the        ammonia vapour dissolves in this equipment.    -   5.—It is also an indispensable requirement for the functioning        of the UAX (200) for the compressed ammonia vapour emerging from        the different gaseous ammonia cooling Elements (204), as well as        the final compressed ammonia cooling Element (205), to be at a        higher temperature than that of the supercritical ammonia        Evaporator (209), so that this heat can be transferred using the        compressed ammonia cooling Coil (206) with which ammonia is        generated in a supercritical state.    -   6.—After relinquishing heat, the ammonia vapour is made to        emerge from the compressed ammonia Coil (206) at the lowest        temperature possible-temperature close to that of saturation in        the compressed ammonia vapour Condenser (207)—and this is then        partially expanded in the Expander (218) to reach the working        pressure of the Condenser (207).    -   7.—In the Condenser (207), the compressed ammonia vapour is        converted into liquid, releasing heat which is transferred in        its entirety to the secondary Generator (202) so that the latter        can perform the partial desorption of the concentrated solution.

To transfer heat from the compressed ammonia vapour Condenser (207) tothe secondary Generator (202), the temperature of the saturation of theammonia vapour that takes place in the compressed ammonia vapourCondenser (207) has to be rather higher than the temperature of thedesorption that takes place in the secondary Generator (202). Given thatthe saturation temperature corresponds to a specific pressure, thelatter is what determines the final pressure of the Compressors (203).

-   -   8.—The ammonia in liquid phase collected in the bottom of the        compressed ammonia vapour Condenser (207) is sent to the        supercritical ammonia Evaporator (209), impelled by the        condensed ammonia Pump (208) at a pressure above that of its        “critical point”.    -   9.—Upon entering the supercritical ammonia Evaporator (209), the        liquid ammonia is first heated and then changes to gaseous state        at a pressure and temperature above those of the “critical        point” of ammonia (113.5 bar/133.5° C.).

The heat the supercritical ammonia Evaporator (209) needs to perform itsfunction is obtained by recuperating the excess heat released by theelements (204), (206) and (211) of the UAX itself, at a temperaturesufficient for this.

-   -   The heat exchanger elements which supply the heat demanded by        the supercritical ammonia Evaporator (209) are the following:    -   The array of cooling Elements (204) between the different stages        of compression.    -   The cooling Coil (206) that cools the compressed ammonia vapour        before it enters the compressed ammonia vapour Condenser (207).    -   The exchanger Element (211) through which part of the hot        concentrated solution that emerges from the ammonia Absorber        (210) circulates.

In order that the UAX can work efficiently, depending energetically onthe Combined Cycle alone, it is necessary to maintain at all times theequality between the amount of heat demanded by the supercriticalammonia Evaporator (209) and that added by the array of exchangerElements (204), (206) and (211), respectively.

In the UAX, this thermal balance is attained and controlled by makingthe Evaporator (209) work at a pressure above that of the critical pointof ammonia. This is a fundamental characteristic that distinguishes theUAX from any other conventional absorption machine.

When working at pressures slightly above that of the critical point ofNH₃ in the Evaporator (209), it is feasible to modify the amount of heatwhich is absorbed here. When the pressure and temperature of the ammoniaexceed its critical point, a “thermal anomaly” appears, in which smallvariations in pressure in the supercritical fluid require large changesin enthalpy for very small variations of temperature (in thePressure-Enthalpy diagram for ammonia, the isotherm lines become almosthorizontal as soon as the critical point is passed).

A direct consequence of the foregoing is that the energy balance in thesupercritical ammonia Evaporator (209) is achieved by making minimalmodifications to the pressure at which it operates. This is achieved inits turn through the joint action of the condensed ammonia Pump (208)and the Expander (217), endowing the system as a whole with anextraordinary flexibility of operation.

-   -   10.—Once the ammonia leaves the Evaporator (209) under        supercritical conditions, it flows to the Absorber (210) as a        result of its own pressure.

In the entry line for gas into the Absorber (210), there is the Valve(217) which is responsible for matching the operational pressure of boththe ammonia Absorber (210) and the supercritical ammonia Evaporator(209).

By regulating the operational pressure of the Absorber (210), thiscontrols the concentration of ammonia in the solution, the operationaltemperature and the heat released in this equipment.

-   -   11.—In addition to ammonia in a gaseous state, the ammonia        Absorber (210) also receives all the dilute solution from the        main Generator (201), after it has been impelled by the transfer        Pump (215) and heated in the heat exchanger Elements (214) and        (216). When the two currents are mixed, this produces the        gaseous ammonia solution by means of which the aqueous solution        increases its concentration of ammonia, giving rise to what we        call the “concentrated solution”. Obviously, for this to happen        as described, the ammonia must always be more soluble in the        Absorber (210) than in the Generators (201 and 202). This is        achieved by making appropriate selections of the operational        pressures and temperatures of the Absorber (210) and the        Generators (201 and 202).

To be able to raise the solubility of the ammonia in water, when thedesign conditions so require, it is possible to add chemical substancescapable of forming complex radicals with the ammonia ion (such as silverchloride, as an example) to the solution.

The solution concentrated in ammonia obtained in the Absorber (210) issent to the Generators (202 and 201) after it has been cooled, thusclosing the working cycle.

As a result of the process of dissolution of the gaseous ammonia, theamount of concentrated solution emerging from the Absorber (210) alwaysexceeds the amount of the dilute solution leaving the main Generator(201).

This is important for the design of the exchangers because theconcentrated solution leaves the Absorber (210) at a temperaturesufficient for its enthalpy to be reusable at the counterflow Exchanger(213/214), on the one hand, and the Heater (211) located inside theEvaporator (209), on the other.

-   -   12.—To carry out this twin heat exchanger function, the current        of concentrated solution emerging, hot, from the ammonia        Absorber (210) is divided into two. On the one hand, a certain        amount of the solution circulates through the heat exchanger        Element (213) to preheat, in counterflow, the dilute solution        that circulates through the heat exchanger Element (214), while        the remaining solution circulates through the concentrated        solution Coil (211) relinquishing heat to the Evaporator (209)        to produce ammonia in a supercritical state.    -   13.—After relinquishing their enthalpy and having been cooled,        the two currents of concentrated solution are combined into one        again before entering the secondary Generator (202).

An Expander (212) element, situated upstream from the secondaryGenerator (202) acts at the pressure at which partial desorption of theammonia contained in the concentrated solution in this equipment takesplace.

-   -   14.—As a result of the partial desorption that takes place in        the secondary Generator (202), a certain amount of humid gaseous        ammonia is given off, which is sent directly to the Compressor        (203).

The heat required by the secondary Generator (202) to desorb the ammoniagas is received by exchange of heat with the compressed ammonia vapourCondenser (207), without any other additional source of heat beingnecessary.

The intermediate concentration solution obtained from the bottom of thesecondary Generator (202) flows to the main Generator (201), which itfeeds, under its own pressure, without need for mechanical means.

-   -   15.—In the main Generator (201), a second phase of desorption in        cascade takes place. As a result of this process. an additional        amount of ammonia vapour is released which is sent directly to        the Compressors (203) together with the vapour obtained in the        secondary Generator (202).

From the bottom of the main Generator (201), a dilute ammonia solutionis obtained (more dilute than that emerging from the secondary Generator(202)) and that is what is sent anew to the Absorber (210) by means ofthe dilute solution transfer Pump (215), thus closing theabsorption-desorption cycle.

The heat that the main Generator (201) needs to conduct the final stageof desorption is supplied from outside the UAX, by exchanging heat withthe Element (107) of the Combined Power Cycle.

The main Generator (201) is the equipment that works at the lowesttemperature of the UAX, being the only point of the cycle by means ofthe UAX receives heat from outside in such a way as to play the role of“cold reservoir” of this heat pump.

In order for the UAX can work efficiently, the operational pressure andtemperature of the main Generator (201) must be meticulously specifiedto satisfy a series of indispensable requirements. On the one hand, itis necessary for the solubility of the ammonia gas under the conditionsof the secondary Generator (202) to be lower than in the ammoniaAbsorber (210) at all times. This is attained by raising the desorptiontemperature: nevertheless, and on the other hand, the purpose of the UAX(200) is to work as a heat pump and, as such, it is of interest for themain Generator (201) that acts as cold reservoir, to do so at the lowesttemperature possible, which means, precisely, that the solubility tendsto rise, contrary to what is intended,

-   -   16.—The dilute solution obtained in the main Generator (201) is        sent to the Absorber (210) so that the UAX works in a closed        cycle. For this, it is required for the transfer Pump (215) that        displaces the dilute solution to do so at pressures above those        of the critical point of ammonia, at which the Absorber (210)        operates.    -   17.—Given that the ammonia Absorber (210) acts as hot reservoir,        to improve the efficiency it is of interest that it can transfer        as much heat as possible to the Reboiler (113) of the Combined        Cycle. This is favoured by having the dilute solution arrive at        the Absorber (210) at the highest temperature possible.

Countervailing this, the efficiency of the UAX is improved when the mainGenerator (201) which acts as cold reservoir receiving heat fromoutside, receives the dilute solution at low temperatures,

To improve the overall efficiency of the UAX (200) and simultaneouslysatisfy both demands, a counterflow heat exchanger is provided betweenthe dilute and concentrated solutions, made up of the heat exchangerElements (214) and (213), respectively.

-   -   18.—The dilute solution, after having been preheated in the        foregoing exchanger, passes through another final additional        heater Element (216) that raises the temperature of this        solution even more, before it enters the ammonia Absorber (210).

As has been mentioned before, the final heater Element (216) for thedilute solution receives heat from the final compressed ammonia coolingElement (205) (which is at the highest temperature in the entire UAX(200)), through which circulates the ammonia vapour emerging from thefinal stage of the Compressors (203).

-   -   19.—This UAX (200) cycle is closed in the Absorber (210) when        the dilute solution mixes with the gaseous ammonia so as to        dissolve this latter, and giving rise to a concentrated ammonia        solution. This is an exothermic process, meaning that it        releases heat. This is the heat that is transmitted to the        exterior Reboiler (113), thus making the Absorber (210) the “hot        reservoir” of the UAX.

Ideally, or in other words, ignoring the inevitable real losses of heatby conduction, convection and radiation, the Absorber (210) is the onlypoint at which the UAX emits heat to the outside.

The process of dissolution of gaseous ammonia that takes place in theAbsorber (210) does so at unusually high temperature and pressure (abovethose of the critical point of NH₃), procuring that the solubility ofammonia in the Absorber (210) is always greater than that in theGenerators (201 and 202).

This is achieved, contrary to what is intended for the Generator (201),by reducing the temperature of the solution: nevertheless and to thecontrary, given that the function of the UAX is to operate as a heatpump, it is intended that the ammonia Absorber (210) that acts as hotreservoir should do so at the highest possible temperature, whichdefinitely does not further a rise in solubility.

-   -   20.—The overall result of the operation of the UAX (200) cycle,        taken together, is that this system works as a heat pump in such        a way that there is a single hot reservoir made up of the        ammonia Absorber (210) and a single cold reservoir comprising        the main Generator (201).

Ignoring the real losses and pursuant to the principle of theconservation of energy and the second law of thermodynamics, the UAXreleases an amount of heat to the Power Cycle through the Absorber(210), equivalent to the sum of the heat that the main Generator (201)captures from the Power Cycle and the mechanical energy the Compressors(203) and pumps of the cycle receive from the power Shaft (130). Thisimplies that a heat pump UAX (200) always relinquishes more heat bymeans of the regenerator Reboiler (113) to the Combined Cycle of theinvention than the heat it has taken from the Combined Cycle of theinvention through the Element (107), this difference in heat being thelesser, the better the performance of the UAX (200) (high CoP isequivalent to high performance). This has direct implications for thePower Cycle because it means that the Reboiler (113) will need to besupplied with an additional quantity of water, as well as all thecondensate produced in the Element (107).

Integration of the Heat Pump (UAX) into the Combined Power Cycle

For the Combined Cycle according to this invention to operate, it isnecessary for the Absorber unit for exchanging heat UAX (200) to beintegrated within a single installation, performing the function of“regenerating” the constituent Brayton cycle, recycling the heatreleased at the coldest point of the cycle to prevent its loss, just asoccurs in other conventional combined cycles.

Regeneration of the constituent Brayton cycle by means of a Heat Pump inthis invention is accomplished by:

-   -   using a condensable thermal fluid (water vapour) instead of a        gas, as happens in normal Brayton cycles,    -   taking a certain amount of mechanical work from the Power Cycle        to make the heat pump UAX (200) function,    -   capturing the condensation heat released from the Power Cycle by        means of the “cold reservoir” of the UAX (200),    -   returning the heat and work received from the Power Cycle by        means of the “hot reservoir” of the UAX (200) generating water        vapour at higher pressure and temperature than those prevailing        previously during the condensation.

To accomplish this class of “regeneration” of the constituent Braytoncycle, the installation avails of:

-   -   a heat exchanger system formed by the Element (107) that        transfers the water vapour condensation heat at ambient pressure        to the cold reservoir of the heat pump UAX (200),    -   the regenerator Reboiler (113) that operates at higher        temperature than the Element (107) generating water vapour at        higher pressure with the heat returned to it by the heat pump        UAX (200) through its hot reservoir,    -   the regeneration condensate Pump (111) that impels the        condensate from the Element (107) to the regenerator Reboiler        (113). The condensed water is sent from the Element (107) to the        regenerator Reboiler (113).

The Regeneration procedure for the constituent Brayton cycle using aheat pump presented in this invention confers two singular advantagesover conventional regenerative Brayton cycles:

-   -   It enables heat released by the constituent Brayton cycle to be        recycled precisely at the point of the cycle where the        temperature is lowest.    -   It regenerates the compressed fluid because the water vapour        condenses at one pressure and the vapour is then regenerated,        but at a higher pressure. This minimises consumption of the        mechanical work of compression necessary to carry the vapour to        the essential heat Source (101) of the constituent Brayton        cycle.

For this type of regeneration using a heat pump (200) to be possible, itis also required for the power Shaft (130) of the installation to supplythe mechanical work of compression necessary for its functioning, thisbeing regarded as an additional self-consumption.

Without considering the real losses and pursuant to the principle of theconservation of energy, the UAX (200), like any heat pump, releases anamount of heat energy through its hot reservoir equal to that which wasabsorbed by its cold reservoir, plus the work consumed by thecompressor. In other words, more heat is always released by the hotreservoir than is absorbed by the cold reservoir. Given that the UAXdoes not exchange energy with outside, this mechanical work ofcompression absorbed from the Power Cycle is later returned in the formof additional heat by the Reboiler (113). For this reason, apart fromall the condensate generated in the Element (107), it is necessary tosupply the Reboiler (113) with an additional amount of water to beevaporated.

In any case, as is logical, it turns out that the higher the performance(CoP) of the heat pump UAX (200), the higher will be the net efficiencyof the Combined Power Cycle.

One singular characteristic of using a variant of the “constituentBrayton cycle” in which a condensable fluid is used is that it enablesthermal fluid to be exchanged with the “constituent basic Rankine cycle”of the Combined Cycle of the invention. In the Combined Cycle which isthe object of this invention, the amount of additional water it isnecessary for the Reboiler (113) to evaporate, with respect to theElement (107), is obtained from currents from the constituent basicRankine cycle or interconnecting lines between the constituent cycles(Brayton and Rankine).

This possibility of interconnecting the constituent Brayton and Rankinecycles of the Combined Cycle of this invention gives rise to other typesof advantages, such as the possibility of simplifying the installationby using elements common to both cycles.

The objective of incorporating a heat pump into the constituent Braytoncycle is to accomplish its “regeneration”, recycling the heat releasedat the coldest point of the cycle and thus preventing its loss. Thistype of regeneration turns out to be feasible only when the Braytoncycle is “closed” or “semi-closed”: in other words, only when thethermal fluid is not expelled to the atmosphere, but returned to thecycle.

-   -   Operation in “closed cycle” is accomplished when the        Installation functions without material being supplied from        outside, in which case the input energy is supplied by        exchanging heat with an external source at a temperature        sufficient for the purpose (this could be of solar or nuclear        origin, to cite examples).    -   Operation in “semi-closed cycle” is accomplished when the input        of energy into the Installation takes place by means of a        process of “internal oxy-combustion” performed in a burner.

In the case that the Combined Cycle is semi-closed, it will have atleast one burner as a source for supplying energy to the Power Cycle.Any burner of the Combined Cycle employs as comburent only industrialpure oxygen diluted in pressurised water vapour in a process known as“oxy-combustion”, in which the gases of this chemical reaction come toform part of the thermal fluid in the burner, Thus, the semi-closedCombined Cycle, apart from employing “oxy-combustion”, also employs“internal combustion”.

Any element or substance other than 02 present in the comburent (such asNitrogen, Sulphur, etc.) is undesirable because it contaminates thethermal fluid and poses operational problems for the Combined Cycle.This precludes the possibility of using air as comburent in thisCombined Cycle.

The semi-closed Combined Cycle can use any fuel meeting the followingrequirements:

-   -   The fuels employed must be liquids or gaseous but never solids.    -   The fuel employed in the burners of the Combined Cycle may        comprise a single substance or be a mixture of several fuels.    -   The chemical composition of the substances employed as fuels        satisfies the generic formula C_(x)H_(y)O_(z), where the letters        C, H and O refer to the elements Carbon, Hydrogen and Oxygen,        respectively, and the subscripts “X, Y, Z” represent the        stoichiometric content of each of those elements pursuant to the        following prescriptions:    -   The subscript “Z” for oxygen in the generic formula may be zero        or any other value. According to this, any hydrocarbon        fulfilling all the foregoing requirements is amenable for use as        fuel in the Combined Cycle.    -   Pure hydrogen can be used as fuel in any case. Nevertheless, for        installations using H₂ as sole fuel, and for reasons of        efficiency and simplicity of the Installation, this needs to be        considered as a special case, according to Configuration-4        (FIG. 4) of the Combined Cycle.    -   case that the subscript “Y” for hydrogen can take the value        zero.    -   Any other chemical compound containing elements other than        Carbon, Hydrogen and Oxygen is undesirable.    -   The fuels amenable to use must be real chemical substances        capable of reacting chemically with oxygen in an exothermic        process of combustion.    -   The chemical reaction of combustion must be conducted without        any other kind of secondary chemical reaction taking place        simultaneously.

In any “semi-closed internal oxy-combustion” process, a continuous inputof matter to the cycle takes place intrinsically (in the form of fueland comburent), so that to establish the matter balance of the cycle, itis indispensable that the amount of matter entering be eliminated inanother part of the cycle in the form of combustion products. As onlythe combustion products are eliminated from the cycle (CO₂ in liquid orgaseous state and liquid H₂O, separately), later processing of these forany kind of industrial use turns out to be very simple, without theemission of greenhouse effect gases entailed by open cycles. In thecycle of this invention, the water emerges in liquid form at ambienttemperature, representing an insignificant environmental impact while,on the other hand, the CO₂ is obtained in a concentrated and confinedform, with no specific procedure for its capture being necessary.

in fact, this particular feature of the Combined Cycle, under which thecombustion products are eliminated “separately, concentrated and at lowtemperature” is one of the fundamental grounds on which the presentPower Cycle yields higher efficiencies than other open combined cyclesof the state of the art.

-   -   One of the fundamental features of the Power Cycle of this        invention that distinguishes it from conventional combined        cycles is its indispensable condition that there be an energy        balance at all times, in that the energy entering the Power        Cycle by means of the heat Sources (101) and (132) must equal        the sum of the energies emerging from the Power Cycle through        the power Shaft (130), as net work of the Cycle, plus the heat        lost through the Sink (128).

Any variation arising between the constituent Brayton cycle, theconstituent basic Rankine cycle, and the UAX must be offset to maintainthis equality by transferring heat between them and, for this, it is anessential condition that there must always exist a temperaturedifferential between one fluid and another permitting this. Otherwise,it will be necessary to evacuate energy from the Cycle, losingmechanical power and/or performance.

One of the fundamental aspects of this invention lies in establishing apermanent energy balance between the Power Cycle and the Heat Pump UAX(200) so that they interchange energy, but there must never existexcesses of heat because these will have to be carried to the outsideenvironment, implying a loss of efficiency.

For the two cycles to work in “symbiosis” in the manner described, it isnecessary for the Power Cycle to be capable of capturing all the heatthat the UAX returns to it by means of its Hot Reservoir (210).

For the reasons set out in the immediately foregoing paragraphs, thepreferred embodiment of the invention is that of configuration 6 whichenvisages the possibility of extracting a certain vapour flow from theElement (112).

In order to apply this vapour flow generated in the Element (112)according to this invention usefully within the Power Cycle, threepossible options are proposed:

A.—Send this vapour flow to an initial additional stage of the vapourCompressor (115) so that this vapour is added to the flow of vapour fromthe Element (114) for them to be compressed together and sent to theessential heat Source (101).B.—Send this vapour flow to a superheater Coil (136) which raises itstemperature for immediate expansion in an additional Turbine (137) whoseoutlet is connected directly to the inlet of the Turbine TBP (127). Inthis case, this additional flow of vapour circulating through theLow-Pressure circuit is returned to the constituent basic Rankine cyclealong a bypass line after the Pump (123).C.—Send one part of this flow of vapour to each of the foregoing optionsA and B, in combination.

These three alternatives are shown in configuration 5—FIG. 6 —.

Particular Advantages of the Installation of the Invention

The fundamental advantages brought by the Combined Cycle of theinvention with respect to other procedures for the generation ofmechanical energy are basically the following:

-   -   With the Power Cycle of the invention, performance as good or        better than that offered today by other available procedures in        the current state of the art is obtained.    -   With the Power Cycle of the invention, a lower environmental        impact than that generated by other available procedures in the        current state of the art is obtained.

The most advantageous singular features characterising the CombinedCycle of the invention are:

-   -   The Combined Power Cycle employs water as thermal fluid common        to all the equipment comprising it. This makes it possible for:    -   The Combined Power Cycle to integrate, at least, one constituent        Brayton cycle and one constituent basic Rankine cycle into a        single cycle. This makes it possible for:    -   The Combined Power Cycle to be capable of working both in closed        cycle and in semi-closed cycle (internal oxy-combustion).    -   The Combined Power Cycle is regenerated using the heat pump.        This makes it possible for:    -   The Combined Power Cycle to perform the capture of the CO₂        (generated in the process of oxy-combustion) as a concentrated        gaseous or liquid residue which is obtained confined in a        specific component of the cycle—Element (107)—.    -   When a CO₂ liquefaction plant is present, integrated into the        installation and performing the function of the Element (107),        the efficiency of the process for obtaining liquid CO₂ turns out        to be very high, because the heat generated in the successive        stages of compression of the CO₂, instead of being lost, is        recouped by transferring it to the cold reservoir (201) of a        heat pump (UAX) capable of reusing it.    -   The Combined Power Cycle (excepting the real losses and the        cogeneration heat) releases heat to the environment through a        single thermal reservoir—heat Sink (128)—. The heat released by        the remaining elements is reused by some other element of the        same cycle.

The integration of an absorption heat pump UAX (200) into the tail ofthe constituent Brayton cycle is a key and innovative element introducedby the Combined Cycle of this invention, The heat pump UAX (200)integrated into the power cycle enables the following characteristiceffects, particularly novel and advantageous, to be achieved:

-   -   1) Enhancement of the overall efficiency of the Power Cycle. The        UAX (200) captures heat from the Power Cycle at its cold        reservoir to reintroduce it into the cycle by its hot reservoir.        This means that there are no losses of heat from the thermal        fluid to the outside in the isobaric cooling stage of the        constituent Brayton cycle. This means that the Condenser (128)        performs the function of the sole heat sink of the Combined        Cycle through which heat is relinquished to the outside.    -   2) Regeneration of the constituent Brayton cycle. This invention        is a novel procedure of “Regeneration” for the constituent        Brayton cycle, according to which, with the heat energy        transferred by the “heat pump” UAX (200), part of the vapour of        the Power Cycle is regenerated.    -   3) Reduction of the mechanical work of compression in the        constituent Brayton cycle. In the Power Cycle, the UAX (200)        achieves an effect equivalent to that of compressing vapour,        because the process of transfer of heat energy performed by the        heat pump implies the condensation of vapour at ambient pressure        (with the heat absorbed by the “cold reservoir”) to later        produce vapour again at a higher pressure (with the heat        released by the “hot reservoir”), at another point of the same        cycle.    -   4) Reduction of environmental impact. In this invention, the        process of sequestration of carbon dioxide is conducted        intrinsically, in that the functioning of the Combined Cycle        itself disposes of this combustion product gas at a specific        point of the Combined Cycle—Element (107)—. By integrating the        heat pump UAX (200) into the semi-closed Combined Cycle of the        invention, the complete condensation of the thermal fluid        (water) is achieved, leaving only the CO₂ free. With this        procedure, the Combined Cycle of this invention does not emit        any kind of gases from combustion directly into the atmosphere.

The overall effect accomplished by coupling the heat pump UAX (200) tothe constituent Brayton cycle is equivalent to compressing its thermalgas, in the sense that, starting from a gaseous fluid it has at lowpressure and temperature, a process (of regeneration) is conducted whichyields this same gaseous fluid but at higher pressure and temperature.The key difference lies in, to obtain this compressed fluid, instead ofmechanical means, a heat pump is employed. The use of a heat pump togenerate a compressed vapour furnishes, additionally, a clearenvironmental advantage when compared with other methods based upon theuse of hydrocarbons as fuel in the current state of the art, because itinduces the capture of the incondensable gases from the combustion,whose emissions entail harmful effects upon the environment.

Provided that fuels are used in a semi-closed oxy-combustion cycle, CO₂is going to be produced, which accompanies the water vapour until it iscooled by the cold reservoir of the heat pump. All this CO₂, which isobtained concentrated and in a gaseous state, is removed from the PowerCycle when all the water vapour it contains has condensed. The captureof the CO₂ generated in the burners of the Combined Cycle takes place asa direct consequence of the operation of the equipment of the cycle, andin no case is any specific procedure to “capture” the CO₂ conducted:that is to say, that even if the capture of CO₂ were not ofenvironmental interest, the Cycle would work in the same manner and theCO₂ captured could be discharged directly into the atmosphere. In thisCycle, the capture of CO₂ is an advantage and not an option.

This means that the capture of CO₂ occurs intrinsically in the PowerCycle as a direct consequence of regenerating the constituent Braytoncycle with a heat pump. With this procedure, no other additionalprocedure to sequester the CO₂ from the combustion in this CombinedCycle is necessary.

Particular Embodiments of the Installation of the Invention

-   -   To successfully maximise performance, it is necessary for the        Combined Cycle of this invention to avail of a series of        additional equipment.

With the objective of improving the overall efficiency of the CombinedCycle, the Combined Cycles corresponding to FIGS. 2, 3 and 4 yieldbasically four types of improvement with respect to the Essential Cycleshown in FIG. 1:

-   -   1.—Increase the pressure in the essential heat Source (101).        This is achieved by raising the pressure of the vapour        regenerated in the Reboiler (113) and to this end, one or more        additional stages of mechanical compression are provided using        certain compressors (115) and (117). This process of compression        is undertaken in several stages with intervening cooling, making        use of the exchanger formed of the Elements (116) and (118).    -   2.—Increase the temperature of the vapour entering the Turbine        TAP (122). This is achieved by providing an additional        supplementary heat Source (132) that raises the enthalpy of the        vapour of the constituent basic Rankine cycle.    -   3.—Use part of the heat held by the outlet gases from the        Turbine TAT (102) for industrial uses unrelated to the Power        Cycle. By doing so, mechanical and useful heat energy are        obtained simultaneously in a process which is known as        “cogeneration”.    -   4.—Reuse part of the heat which is released at the heat Sink. It        turns out to be feasible to successfully enhance the performance        of the Combined Cycle of this invention when the heat sink is        made up of a heat recovery circuit that generates vapour in        another secondary Rankine cycle at lower pressure than the        constituent basic Rankine cycle. To attain this, the present        invention proposes four different types of configurations        (represented in FIGS. 2, 3, 4 and 6).

These four types of improvements to the Combined Cycle are mutuallycompatible in their entirety. Nevertheless, with regard to the fourthtype of improvements indicated above, it should be said that there existdifferent methods for reusing the heat released by the essential sink ofthe Cycle—Condenser (128) Element of FIG. 1—replacing this by asecondary Rankine cycle in such a way as to harness part of the heatcaptured to convert it into work using the Turbine TBP (127), and insuch a way that the Condenser of this secondary Rankine cycle passes toperforming the indispensable role of “sink” for the heat of the CombinedPower Cycle. There exist four different configurations of the CombinedCycle, depending on how the secondary Rankine cycle is integrated. Thesethree configurations correspond to FIGS. 2, 3, 4 and 6 respectively.Each of these configurations consists of particular equipment andelements, detailed later on, where the particularities of eachconfiguration are set out separately.

To accomplish the first three types of improvements, the Combined Cycleof the invention is designed to include a series of additionalequipment. It is important to emphasise that the additional equipment isthat not forming part of the essential basic cycle, and these are sodesigned as to operate in a way to implement different versions of theCombined Cycle which are more efficient and confer additional advantagesbeyond those brought by the essential configuration pursuant to FIG. 1.

The fourth type of improvement mentioned above is founded upon partialreuse of the heat released in the heat Sink, availing in its place of asecondary Rankine cycle. This invention envisages four types ofconfigurations, depending on how the secondary Rankine cycle isintegrated into the Combined Cycle. Each of these configurationsrequires its own additional equipment, as will now be detailed.

The additional equipment making up the different versions of theCombined Cycle according to this invention are as follows:

115: First water vapour Compressor. This Compressor (115) undertakes afirst stage of compression of the water vapour from the condensationheat exchanger Element (114). Moreover, in those cases in which thedesign of the Installation so envisages, there exists the possibilitythat a certain amount of vapour generated in the Element (112) iscompressed in a first additional stage of the Compressor (115). In thisparticular case, that first additional stage in the Compressor (115) isrequired because the pressure of this vapour generated in this Element(112) is always lower than that of the vapour entering the Compressor(115) from the Element (114).

The thermodynamic performance of the Power Cycle rises as the pressurein the Turbine TAT (102) increases, and this is achieved by raising thepressure of the vapour entering the essential heat Source (101). To getthe water vapour to reach the essential heat Source (101) at a higherpressure than that of the vapour generated in the Reboiler (113), it ispossible to use additional mechanical means. For this, the Compressor(115) which increases the pressure of the water vapour emerging from theside of the exchanger (114) is provided, employing mechanical workobtained from the power Shaft (130) of the installation.

When the vapour is compressed, this increases the temperature (due tothe Joule-Thomson effect), although the process of mechanicalcompression is more efficient as the gas being compressed is colder. Theconclusion to be drawn from this is that the thermodynamic performanceof the process of compression is greater when it is carried out inmultiple stages. For this reason, the vapour emerging from theCompressor (115) is sent for cooling to the heat exchanger Element (116)before the next stage of compression is conducted.

Vapour Cooling Exchanger Between Stages of Compression Consisting of theElements (116) and (118):

116: Shell side of the vapour cooling exchanger between stages ofcompression. This Element (116), together with the heat exchangerElement (118), forms a heat exchanger. The outlet vapour from theCompressor (115) is cooled by circulating it through an Element (116)before passing to the next Compressor (117) so as to improve themechanical efficiency of this equipment. Inside it, there is the heatexchanger Element (118), through which condensate obtained from thebottom of the element (114) circulates and serves as refrigerant.

118: Vapour cooling Element between stages of compression. This heatexchanger Element (118) together with the heat exchanger Element (116)forms a heat exchanger. This heat exchanger (116/118) will always existprovided that a second Compressor (117), in cascade with the first one(115), is available. In the case that the Installation does not have theCompressor (117), the exchanger (116/118) is optional.

The heat exchanger Element (118) is a coil or any other heat exchangerelement through which water circulates, that serves as refrigerant tocool the vapour between the successive stages of mechanical compressionperformed by the Compressors (115) and (117). The condensate Pump (129)impels the water that circulates through this heat exchanger Element(118) and the current emerging from this is sent to the essential heatSource (101).

117: Final water vapour Compressor. Made up of another additionalcompressor connected in series with the preceding Compressor (115). ThisCompressor (117) receives the cooled vapour from the Element (116), andfrom it emerges vapour at sufficient pressure to feed the essential heatSource (101).

It is obviously also feasible to compress the vapour using only onevapour compressor and conduct this operation in just one stage.Therefore, there exists the option of forgoing this additional vapourCompressor (117), but it if does exist, it will always be connected inseries with the Compressor (115) after the intermediate coolingexchanger (116/118).

131: Auxiliary heat exchanger Element for preheating of fuel andcomburent (prior to their entry into burners). This is a tubular pipe,coil or other heat exchanger element through which circulates anauxiliary fluid located, optionally, according to the particular designrequirements of the Installation, after some Low-Pressure Evaporator(125) element, or inside the condensation heat exchanger Element (114),and from which it absorbs heat which is used to preheat, separately,both the fuel and the comburent above the conditions of their supply tothe temperature at which they are sent to the oxy-combustion burners.

Apart from being used to preheat the fuel and comburent of the CombinedCycle, the heat from the Coil (131) can be destined for any otherapplication independent of the Power Cycle, in which case, and for allpurposes this is deemed to be “cogeneration”.

132: Supplementary heat Source. When a supplementary heat Source (132)is incorporated, it is situated immediately after the tubular pipes ofthe Evaporators and Superheaters (121) for the vapour at the exit fromthe CRC (103) and its mission is to raise the enthalpy of the vapour inthe constituent basic Rankine cycle for it to enter the Turbine TAP(122) with a higher level of superheating.

When the Combined Cycle is “closed”, the supplementary heat Source (132)consists of an additional heat exchanger that receives heat from anexternal source. When the Combined Cycle is “semi-closed”, thesupplementary heat Source (132) can be an additional oxy-combustionburner that operates at higher pressure than the essential heat Source(101).

133: Heat exchanger Element for cogeneration. This comprises a tubularheat recovery circuit for use in external applications of cogenerationbeyond the Power Cycle. Therefore, it works by circulating a fluidindependent of the rest of the installation.

The heat exchanger Element (133) represents an additional focus of heatby which heat is released outside the Combined Cycle, but this isconsidered as useful heat that is given industrial uses. Indeed, it isconsidered that the heat energy extracted form the Power Cycle by theheat exchanger Element (133) emerges at temperature sufficient to put itto use in different types of common industrial processes in a range thatcould run between 175° C. and 600° C., depending on the design of theinstallation.

In some cases, depending on the pressure and temperature variables withwhich the Cycle is designed, it is required that the heat exchangerElement (133) should extract heat from the CRC (103) so it can establishthe energy balance of the cycle permanently (especially when theCombined Cycle has two heat sources).

In accordance with the unavoidable requirements to have to establish theenergy balance, the amount eliminated from the Cycle in the form ofcogeneration heat is determined by the needs of the Combined Cycle andnot by the thermal demand from any equipment of external consumption,unless the Combined Cycle has some additional internal system enablingit to modify its energy balance.

Whether or not there is a cogeneration coil (133) to extract heat fromthe CRC (103), the Combined Cycle of this invention can include an“auxiliary heat relief system” made up of two additional pieces ofequipment—Reheater (134) and Turbine TPI (135)—which are provided toestablish the energy balance that must be maintained permanently in theinstallation, reducing the amount of vapour entering toward the heatSources (101) and (132), and consequently to the CRC (103) as well. Inother words, it is possible to alleviate the heat by modifying theinternal functioning of the cycle instead of having to shed heat to theoutside.

The “auxiliary heat relief system” is formed by a vapour extractiondevice at the outlet of the Turbine TAP (122), which circulates throughthe Reheater (134), then through the Turbine TPI (135) and finallyreintroduces the outlet vapour into the final section of the CRC (103).

The “auxiliary heat relief system” is useful as a way to dampen theenergy imbalances that arise during the normal operation of the CombinedCycle, and even changes in load. For certain design configurations,especially in those cases where a double heat Source (101) and (132) isavailable, this equipment may become indispensable.

The “auxiliary heat relief system” uses as its working fluid one part ofthe water vapour belonging to the constituent basic Rankine cycle, sothat when present it is considered to form part of this.

134: Auxiliary Reheater of the constituent basic Rankine cycle. TheReheater (134) is found inside the CRC (103) itself and is made up of atubular circuit that heats the vapour extracted from the outlet of theTurbine (122) and immediately sends it to the auxiliary Turbine TPI(135).

135: Auxiliary intermediate-pressure Turbine TPI of the constituentbasic Rankine cycle. The function of this steam Turbine is to generatework, following the constituent basic Rankine cycle.

The Turbine TPI (135) receives vapour from the outlet of the Turbine TAP(122) after it has been previously reheated in the Reheater (134) toincrease the mechanical efficiency.

It is characterised by being the turbine that works at a pressure lowerthan the Turbine TAT (102) and higher than the Turbine TBP (127) so thatit is denoted by its initials in Spanish TPI (Intermediate PressureTurbine). This Turbine works at back pressure, in other words, carryingout a partial expansion of the vapour so that the outlet is atsufficient pressure for the vapour to be introduced at a certain pointof the CRC (103) (where the temperature of the vapour entering theconduit and the temperature of the gases circulating through the conduitmatch).

In order that certain high-efficiency designs of the Power Cycle canwork coupled to low-efficiency heat pumps UAX, without needing totransmit losses to the exterior, it is necessary that an additionalcurrent of water vapour should emerge from the Element (112) (atpressure above atmospheric).

Thus, the Power Cycle can transform the amount of excess heattransmitted to it by the UAX into a certain amount of vapour.

There exists the option of sending this vapour generated in the Element(112) directly to the Compressor (115). This option does not requireconsidering any additional equipment, and it is only required to endowthe Compressor (115) with means to carry out a first additional stage ofcompression so as to match the pressure of the vapour entering from theElement (114).

Configuration-2 and Configuration-3 are the most appropriate for thedesign of oxy-combustion Combined Cycles which use, in addition tohydrogen, the other possible fuels containing carbon, because theircombustion gives rise to carbon dioxide. The presence of this gasrequires that the secondary Rankine cycle should be independent of therest of the Power Cycle because incondensable gases prevent the “vacuum”pressures necessary to operate economically from being reached. In theseconfigurations of the Combined Cycle that include an independentsecondary Rankine cycle, there is the possibility that the latterRankine cycle should use thermal fluids other than water such as, forinstance, the ORC (Organic Rankine Cycles) that use organic fluids asthermal fluid.

The vapour generated in this independent secondary Rankine always worksat a pressure below that of the constituent basic Rankine cycle becauseits temperature is very different. With the steam produced in thesecondary Rankine cycle, the Turbine TBP (127) is moved, and thisprovides additional work to the power Shaft (130) of the Combined Cycle.Subsequently, the steam emerging from this Turbine TBP (127) passes to aCondenser (128) which genuinely carries out the function of heat sink,so that the resulting Combined Cycle loses energy, transferring it tothe outside. The condensate obtained in the bottom of the Condenser(128) is impelled by the Pump (123) to the Economiser (124), Evaporator(125) and Superheater (126) in succession before it is returned to theTurbine (127) and thus closing the cycle. When the Installation has aSuperheater (136) and a Turbine (137) for regenerated steam, thereexists a bypass line along which this additional vapour, after thecondensate Pump (123), returns to feed the Brayton and basic Rankinecycles.

Configuration 2

The installation of the invention according to additional embodimentscorresponding to Configuration-2, shown in FIG. 2, is characterised bythe following:

-   -   It includes an independent secondary Rankine cycle that uses its        own thermal fluid, independently of the rest of the Power Cycle.    -   The heat recovery Conduit CRC (103) works at pressure above        atmospheric.    -   Condensation of vapour takes place in the final section of the        CRC (103) where the temperature of the gases is lower.

The mode of operation of the installation according to Configuration-2consists basically of providing an Evaporator circuit belonging to anindependent Rankine cycle in the interior of the heat recovery ConduitCRC (103). This Evaporator circuit generates its vapour with the heatfrom the condensation that takes place in the final section of the CRC(103) where the temperature is lower, The condensed water obtained inthe bottom of this CRC (103) is sent to an external exchanger (108/124)where the heat the condensate holds is transferred to the Economiser(124) of the secondary Rankine cycle.

Configuration-2 includes all the elements of configuration 1, and inaddition, the following:

108: Shell side of the economiser exchanger of the secondary Rankinecycle. The Element (108) makes up a heat exchanger together with theEconomiser (124). Through the heat exchanger Element (108) circulatesthe condensate collected, either from the bottom of the heat recoveryConduit CRC (103) or from the bottom of the Conduit (105), in accordancewith the design in question, transferring heat to the Economiser (124)of the secondary Rankine cycle.

124: Economiser of the secondary Rankine cycle. Together with the heatexchanger Element (108), this constitutes a heat exchanger. TheEconomiser (124) is the heat exchanger element of the secondary Rankineelement deployed inside the heat recovery Element (108) from which itreceives heat, raising the temperature of the condensate (to bring itclose to its boiling point) that it returns to the Condenser (128)impelled by the secondary Rankine cycle feed Pump (123).

123: Secondary Rankine cycle feed Pump (low pressure). This is the Pumpthat impels the thermal fluid from the Condenser (128) to the Economiser(124) of the secondary Rankine cycle.

125: Secondary Rankine cycle Evaporator (low pressure). This is the heatexchanger element provided—according to Configuration-2—in the lastsection of the heat recovery Conduit (103) from which it receivescondensation heat. Its mission is to receive the fluid from theEconomiser (124) and convert it into vapour for the secondary Rankinecycle.

When the Installation is designed according to Configuration-5, theEvaporator (125) of the secondary Rankine cycle can be divided into twosections connected in parallel.

126: Secondary Rankine cycle Superheater (low pressure). This is theheat exchanger element provided inside the recovery Conduit CRC (103)and whose mission is to raise the temperature of the vapour generated inthe Evaporator (125) element of the secondary Rankine cycle before itenters the Turbine TBP (127).

127: Secondary Rankine cycle Turbine (low pressure) TBP. This is theTurbine of the secondary Rankine cycle that furnishes additionalmechanical work to the power Shaft (130). The Turbine TBP (127) receivesthe vapour from the Superheater (126) and the output vapour is sent tothe Condenser (128) which acts as the heat sink for the Combined Cycle.

Optionally, Configuration-2 can include all the elements mentioned abovein the section entitled “particular embodiments of the installation ofthe invention”.

Configuration 3

The installation of the invention according to additional embodimentscorresponding to Configuration-3, shown in FIG. 3, is characterised bythe following:

-   -   It includes an independent secondary Rankine cycle that uses its        own thermal fluid, independently of the rest of the Power Cycle.    -   The heat recovery Conduit CRC (103) works at ambient pressure.    -   There is no condensation of vapour in the CRC (103) unless an        independent condensation Conduit (105) is provided for that        purpose.    -   It includes a Fan (104) that extracts the gases from the CRC        (103) and compresses them in such a way that the condensation        Conduit (105) operates at a higher pressure than that of the        output from the CRC (103).

The fundamental difference with respect to Configuration-2 consists inthe fact that in its operation in Configuration-3, the recovery ConduitCRC (103) works at a lower pressure (generating a greater amount of workat the Turbine TAT (102) and making the input temperature of gases intothe CRC (103) lower) and then, by means of the Fan (104), the gasesemerging from this Conduit are compressed to get the condensationtemperature of the steam to rise and thus raise the working pressure ofthe secondary Rankine cycle. By successfully transmitting heat at ahigher temperature to the secondary Rankine cycle, it increases themechanical work generated by the Turbine TBP (127).

This Configuration-3 includes, in addition to all the elements includedin Configuration-2, the following:

104: Fan. This is an induced-draft Fan situated at the outlet of thegases from the heat recovery Conduit (103), that separates thecondensation zone of the heat recovery Conduit CRC (103) by situating itin an independent condensation Conduit (105). The Fan (104) produces anincrease in the pressure of the vapour aspirated by the CRC (103) bygetting the saturation temperature of this vapour to rise. This increasein the vapour saturation temperature on the side of the Conduit (105)means that the vapour of the secondary Rankine cycle can be generated ata higher temperature, which leads to an improvement in efficiency.

Provided that the Installation has a Fan (104), the Evaporator (125) ofthe secondary Rankine cycle can be divided into two sections working inparallel, one of them situated in the Conduit (105) and another in theConduit (103) after the Economiser (120). This design alternative isfeasible in any of the configurations 2, 3 and 5, although it is onlyrepresented in configuration 5 (FIG. 6).

105: Independent condensation Conduit. This is a section of the heatrecovery conduit in which water vapour contained in the gaseous phaseemerging from the CRC (103), impelled by the Fan (104), condenses.

Unlike what happens in Configuration-2, in Configuration-3, theEvaporator (125) belonging to the secondary Rankine cycle is locatedinside the section of the condensation Conduit (105) with whichcondensation heat is exchanged to generate the vapour of the secondaryRankine cycle.

When the cycle is designed according to Configuration 5, the Evaporator(125) is made up of two sections that work in parallel: one within theConduit (103) and another within the Conduit (105).

Configuration 4

The installation of the invention according to additional embodimentscorresponding to Configuration-4, shown in FIG. 4, is characterised bythe following:

-   -   It includes a secondary Rankine cycle that uses the thermal        fluid common to the rest of the Power Cycle.    -   The secondary Rankine cycle does not have economisers,        evaporators or superheaters.    -   The heat sent to the Turbine TBP (127) is obtained directly by        extracting it from the heat recovery Conduit CRC (103).    -   The condensate obtained from the secondary Rankine cycle is        employed directly as feedwater to the rest of the Combined        Cycle.

Configuration-4 is a design simplification of the Combined Cycle inwhich the steam circulating through the Combined Cycle is also used asthe fluid of the secondary Rankine cycle that is possible, alwaysprovided there is no presence of CO₂ or other incondensable gases at anypoint of the Combined Cycle. This only happens when the installation isdesigned to work on a closed cycle and when hydrogen is the only fuelpossible.

It should be said that hydrogen can be used as fuel in any of thepossible configurations of the Combined Cycle although, when hydrogen isused as the only fuel, it is preferred to use this version of the design(as shown in FIG. 1) because it is simpler and may be more efficient.

In this Configuration-4 of the Power Cycle, the secondary Rankine cycleworks with the same fluid as the rest of the Combined Cycle. The vapourof the secondary Rankine cycle according to this Configuration-4 isobtained from a current extracted directly from the Conduit CRC (103),which is sent directly to the Turbine TBP (127) of the secondary Rankinecycle and, on the other hand, condensate obtained from the Condenser(128) is returned directly to feed the rest of the Combined Cycle usingthe Pump (109). A direct consequence of this is that in this designversion, there are no heat exchanger elements generating their ownvapour: that is to say, there are neither Economiser (124), Evaporator(125), nor Superheater (126)

In this configuration, the Secondary Rankine cycle feed Pump (123) isalso dispensed with because the Pump (109) returns the condensatedirectly from the Condenser (128), as feedwater for the rest of theCombined Cycle.

When a semi-closed cycle is implemented with hydrogen as fuel inaccordance with Configuration-4, water is the only product obtained fromthe combustion, and is eliminated from the cycle in liquid form fromthis condensate return line (just as happens in the rest of theconfigurations).

When a closed cycle is implemented in accordance with Configuration-4,there are no burners which supply matter to the Combined Cyclecontinuously, and therefore no type of residue is obtained continuouslyfrom it either.

In view of this, the only equipment of the Combined Cycle through whichthere can be circulation of CO₂ is:

When the main heat Source (101) is made up of a burner (of some fuelother than H₂): The Burner (101) itself, the Turbine TAT (102), the CRC(103), the condensation exchanger Element (106) and finally, the Element(107) whence the CO₂ is eliminated from the cycle.

When the Power Cycle has another burner playing the role ofsupplementary heat Source (132), in addition to all the equipment citedpreviously, there is circulation of CO₂ through the supplementary Burner(132), the Turbine TAP (122), the Reheater (134) and the Turbine TPI(135)—considering that the Power Cycle can also include the latter twooptional elements—

When the Power Cycle is implemented according to Configuration-3, inaddition to in the foregoing equipment, there is circulation of CO₂through the Fan (104) and the condensation exchanger Element (105).

According to an additional alternative, this vapour generated in theElement (112) can be carried to the Secondary Rankine Cycle to befinally expanded in the Turbine TBP (127).

-   -   This option corresponds to the additional embodiments with        Configuration-5, shown in FIG. 6,    -   Configuration-5 is the preferred embodiment of this invention as        it is the most complete and because it includes all the elements        of which this invention consists, whether these elements are        considered to be essential or optional. It enables both closed        cycle and semi-closed cycles to be implemented, using any type        of fuel that the remaining configurations can employ.

Configuration-5 includes all the elements of configuration 3, and inaddition, requires two specific pieces of equipment:

136: Superheater for the vapour generated in the Element (112). Thiselement (136) consists of a coil situated inside the CRC (103) whichreceives saturated vapour from the Element (112), and whose mission isto raise its temperature so it can then be expanded in another Turbine(137) before it enters the Secondary Rankine Cycle.

137: Turbine for the vapour generated in the Element (112). This Turbine(137) consists of an additional turbine whose outlet vapour pressurematches the pressure and temperature of the vapour entering the TurbineTBP (127). When it expands in the Turbine (137), the vapour generatesadditional work which is furnished to the common power Shaft (130) andthe outlet of this turbine connects with the inlet to the Turbine TBP(127) to continue expanding together with the vapour of the secondaryRankine cycle from the Superheater (126).

To establish the essential matter balance, whenever additional vapour isintroduced into the secondary Rankine cycle, it is required that thereexists a bypass line in the impulsion line of the Pump (123) whichreturns this flow to feed the constituent basic Rankine cycle in theform of water in a liquid state.

In all the cases in which the Installation has a Superheater (136) and aTurbine (137) for the regenerated vapour, there is a bypass line to theaspiration of the Pump (109) after the impulsion line of the condensatePump (123)

For the Compressor (115) to work according to this Configuration-5 shownin FIG. 6, it is necessary for this Compressor (115) to have anadditional first stage of compression to raise the pressure of thevapour entering it from the element (112) and match this with thepressure of the vapour entering the Compressor (115) from the Element(114).

The Installation according to the invention, whatever its designconfiguration, can be connected energetically with the outside only via:

-   -   the heat Sources (101) and (132) as the only possible entry        points for energy into the Combined Cycle;    -   The points by which energy leaves the cycle, in addition to the        inevitable real losses: the heat lost through the Sink (128),        the net mechanical work obtained from the power Shaft (130) and        the useful heat obtained for “cogeneration”.

Determination of the Maximum Theoretical Performance of the Installationof the Invention in Semi-Closed Cycle

The maximum theoretical performance of an Installation generating usefulenergy from heat energy from fuels according to the invention can beestimated very simply and approximately using the present procedure:

As an example, the calculation of the theoretical performance of thecycle of the invention, employing only pure hydrogen as fuel, is carriedout, with the following considerations:

-   -   The “useful energy” produced by the Installation is considered        to be the sum of the heat taken from the CRC (103) for use        external to the cycle in the form of “cogeneration” by means of        the Element (133), plus the net mechanical work emerging from        the Combined Cycle through its power Shaft (130),    -   It is considered that there are no “real losses” and the        Combined Cycle only loses heat energy through the Condenser        (128) that performs the function of heat sink.    -   The calculations are taken to refer to 1 Kg of condensate in the        return line with:        -   “X” the specific fuel: the number of kg of fuel burned for            each 1 kg of “return condensate” water that returns to the            cycle after the vacuum Condenser (128);        -   “PCS” the higher heating value of H₂, whose value is            considered to equal 142,200 kj/kg        -   “PCI” the lower heating value of H₂, whose value is            considered to equal 120,240 kj/kg

“PCS_(H2O)” is determined as the higher heating value of the specificfuel (for each 1 kg of water generated), considering that in thecombustion reaction, for each 1 kg of H₂ that is burned, instoichiometric terms, 9 kg of H₂O are formed, so that:

PCS_(H2O)=15,800 kj/kg_(H2O generated)

PCI_(H2O)=13,360 kj/kg_(H2O generated)

“ΔH_(VC)” is determined as the specific vapour condensation enthalpy gapin the heat Sink (128), considering the calculation for a notionaltheoretical Condenser implementing a vapour condensation enthalpy gapcoinciding with the difference between PCS_(H2O) and PCI_(H2O), then:

ΔH _(VC)=PCS_(H2O)−PCI_(H2O)=2440 kj/kg_(H2O)

“M_(V)” is determined as the amount of “condensed” vapour in the heatSink (128); this quantity will be equal to 1 kg of water that isreturned to the cycle, plus the amount of water formed in the combustionof H₂ (X) and which must be eliminated from the cycle:

M _(V)=1+X (kg_(H2O))

“Lost energy” is determined, as the energy eliminated in the Condenser(128):

Lost energy=M _(V) *ΔH _(VC)=(1+X)*(ΔH_(VC))=(1+X)*(PCS_(H2O)−PCI_(H2O))

Lost energy=(1+X)*2440 kj/kg_(H2O)

The “Useful energy” of the cycle is determined, considering that “theenergy entering is the same as the energy leaving the Cycle”.

Useful energy=Combustion energy−Heat eliminated in Sink(128)

Useful energy(kj/kg_(H2O))=(X*PCS_(H2O))−2440*(1+X)=X*(PCS_(H2O)−2440)−2440

Useful energy (kj/kg_(H2O))=(X*PCI_(H2O))−2440

The Performance of the Installation “η_(PCS)” with respect to the PCS isdetermined from the equation:

${\eta\;}_{PCS} = {\frac{{Useful}\mspace{14mu}{energy}}{{Combustion}\mspace{14mu}{energy}} = \frac{( {X*{{PC}I}} ) - 2440}{X*PCS}}$${\eta\;}_{PCS} = {\frac{PCI}{PCS} - {\frac{2440}{PCS} \star \frac{1}{X}}}$

Replacing PCS_(H2O) and PCI_(H2O) by their numerical values:

${\eta\;}_{PCS} = {\frac{13360}{15800} - {\frac{2440}{15800} \star \frac{1}{X}}}$${\eta\;}_{PCS} = {{0,8456} - {0,1544*\frac{1}{X}}}$

The Performance of the Installation “η_(PCI)” with respect to the PCI,which is what is habitually used as reference, is given by theexpression:

${\eta\;}_{PCI} = {\frac{{Useful}\mspace{14mu}{energy}}{PCI} = \frac{( {X*{PCI}} ) - {2440}}{X*{PCI}}}$${\eta\;}_{PCS} = {\frac{PCI}{PCI} - {\frac{2440}{PCI} \star \frac{1}{X}}}$

Replacing PCI_(H2O) by its numerical value:

${\eta\;}_{PCI} = {1 - {\frac{2440}{13360} \star \frac{1}{X}}}$${\eta\;}_{PCS} = {1 - {0,01826*\frac{1}{X}}}$

The two final equations for the performance η_(PCS) and η_(PCI), give avery approximate result for the performance of the Combined Power Cycleof the invention. While it is true that these are not rigorously exact,these expressions yield the following conclusion: the performance of theCombined Cycle of the invention varies directly with the specific fuelburned. That is, the performance of the cycle rises as the specificconsumption of fuel in the cycle does.

Nevertheless, it is not feasible to increase the specific consumption offuel if a series of fundamental thermodynamic constraints to which theCombined Cycle is inexorably subject are not satisfied.

-   -   One of these fundamental constraints is that, in the Combined        Cycle, it is imperative to fulfill the principle of conservation        of energy, according to which the energy entering the Combined        Cycle is always identical to the energy that leaves it. Pursuant        to this principle, increasing the specific consumption of fuel        could mean, depending on the design parameters of the Power        Cycle, an excess of calorific energy which cannot be captured by        the Evaporator and Superheater (121) of the constituent basic        Rankine cycle, in which case it will be indispensable to provide        some procedure for evacuating heat to the outside and/or some        way of reducing the entry of heat into the CRC (103).

Some of the embodiments of the Combined Cycle described earlier whichmust unavoidably evacuate one part of the heat outside the CombinedCycle can avail of a heat exchanger Element (133) to carry out thisfunction of evacuating heat to the outside, but doing so at atemperature sufficient for this to be useful for meeting the heat demandof certain industrial processes, thus constituting a procedure of“cogeneration”.

In those situations in which it is unavoidable to reduce the entry ofheat into the CRC (103), which can occur, especially at transitorymoments or under changes of load, the configurations of the Power Cyclecan avail of a “vapour relief system” at the outlet from the Turbine TAP(122) which reduces the amount of vapour entering the heat Sources (101)and (132) and therefore also entering the CRC (103). Such a vapourrelief system increases a Reheater (134) and an auxiliary Turbine TPI(135) whose outlet vapour ends up being injected at some point of thefinal section of the CRC (103). It should be highlighted that thisvapour relief system to the heat Sources does not represent any kind ofimprovement with respect to the mechanical performance of the CombinedCycle, although it can be very useful to enable the Installation to bemodulated and change its load and, in addition, it makes possiblecertain design configurations of the Combined Cycle with a twin heatsource and a very high yield of useful energy.

1. An installation to generate mechanical energy using a Combined PowerCycle including at least: means to implement a closed or semi-closedregenerative constituent Brayton cycle which uses water as thermalfluid, means to implement at least one Rankine cycle, the constituentbasic Rankine cycle, interconnected with the regenerative constituentBrayton cycle, and a heat pump (UAX) which makes up a closed circuitthat regenerates the regenerative constituent Brayton cycle;
 2. Aninstallation for the generation of energy according to claim 1, whichincludes an essential heat Source (101), which is selected from: a heatexchanger and an oxy-combustion burner, such that in the cited essentialHeat Source (101), currents from the two cycles, the constituent Braytonand the constituent basic Rankine, come together.
 3. An installation forthe generation of energy according to claim 1, in which the regenerativeBrayton cycle is semi-closed, with oxy-combustion and intrinsic captureof CO₂.
 4. An installation for the generation of mechanical energy,according to claim 2, which also includes: an element (107), selectedfrom: a regeneration condenser, by which the installation transmitsenergy to the cold reservoir (201) of the heat pump UAX, which condensesin one simple stage and a CO₂ liquefaction plant which receives workfrom the power shaft (130) and condenses gases in multiple stages andonly transfers the heat released in the successive stages of compressionof that CO₂ liquefaction plant to the cold reservoir (201) of the UAX, aReboiler (113), with which heat is returned to the Power Cycle from thehot reservoir (210) of the heat pump UAX, a regeneration condensate Pump(111), which drives the condensate obtained in the bottom of theregeneration Condenser (107), and makes it flow towards the Reboiler(113), a heat recovery Conduit (CRC) (103), with which water vapour isgenerated, at least two turbines, one of which is a high-pressureTurbine TAP (122), which sends water vapour to the essential Heat source(101), and another high-temperature Turbine TAT (102), which sendsvapour to the heat recovery Conduit (103), at least one common PowerShaft (130), from which the useful mechanical energy of the cycle isobtained, a system which performs the function of a heat drain bycondensing vapour in the bottom of, or after, the CRC (103), acondensate return Pump (109), a feedwater Pump (119) for the constituentbasic Rankine cycle, a vapour generator for the constituent basicRankine cycle consisting of: economiser Coils (120), Evaporators andSuperheaters for the water vapour (121) situated inside the heatrecovery Conduit (103), one condensation heat exchanger Element (106),before the entry of vapour and gases to the regeneration Condenser(107), which relinquishes heat to a condensate return Preheater (110),one condensation heat exchanger Element (114), provided at the outlet ofthe Reboiler (113), which relinquishes heat to an Element (112) selectedfrom: a Preheater (112) for the intake water to the Reboiler itself(113) and a heat recovery exchanger (112) which in addition topreheating the intake water for the Reboiler (113) itself, heats thefeedwater for the pump (119) and generates a vapour which is directed:to a compressor (115) and/or to a turbine (137) after its temperaturehas been raised in a superheater (136), one bypass line that joins theconstituent Brayton cycle with the constituent basic Rankine cycle,situated between the impulsion line of the regeneration condensate Pump(111) and the aspiration of the feedwater Pump (119).
 5. An installationfor the generation of energy, according to claim 4, in which the PowerCycle is semi-closed, using oxy-combustion, in the event that it employscarbonated fuels, which includes: an outlet for the CO₂ produced in thecombustion, situated in the element (107), and an outlet for the liquidwater produced by the combustion in the condensate return line from thebottom of the boiler.
 6. An installation for the generation of energy,according to claim 4, in which the power cycle is closed or semi-closed,uses oxy-combustion, in the case that it uses hydrogen as its sole fuel,in which the heat sink consists of a secondary Rankine cycle with thesame fluid as the rest of the power cycle, being interconnected with theinstallation by means of the impulsion line of the condensate returnPump (109) and by a line that reaches the heat recovery Conduit CRC(103).
 7. An installation for the generation of energy, according toclaim 4, that includes an element for the supply of additional heat(132) situated between the final superheater (121) and the turbine(122).
 8. An installation for the generation of energy, according toclaim 4, that also includes one vapour compressor (115) or severalvapour compressors (117), connected in series, situated at the vapouroutlet of the exchanger Element (114), and prior to the entry of vapourinto the essential heat Source (101).
 9. An installation for thegeneration of energy, according to claim 8, which also includes a vapourcooling exchanger (116/118) between the Compressors connected in series(115) and (117).
 10. An installation for the generation of energy,according to claim 4, which also includes, in the condensate line fromthe bottom of the condensation exchanger Element (114), a return line tothe Reboiler (113) along which part of this condensate is sent to theReboiler itself.
 11. An installation for the generation of energy,according to claim 4, which also includes a heat exchanger Element forcogeneration (133) provided inside the heat recovery Conduit (103) fromwhich it extracts useful heat energy which could be destined forexternal use in any type of industrial application.
 12. An installationfor the generation of energy, according to claim 4, which also includesan auxiliary heat relief system formed by: a vapour Reheater (134) thatreceives vapour extracted from the Turbine TAP (122) and an auxiliaryTurbine TPI (135) whose outlet vapour is injected at some point of thefinal section of the CRC (103).
 13. An installation for the generationof energy, according to claim 4, including, in addition: a Fan (104),which takes the outlet vapours from the heat recovery Conduit CRC (103)and compresses them to send them to a condensation exchanger (105),housing at least one component section of an evaporator (125) of anindependent secondary Rankine cycle.
 14. An installation for thegeneration of energy, according to claim 4, including, in addition: aheat Exchanger (108/124) in which, on the shell side (108), thecondensate from the Conduit (105) is cooled, and in whose interior thereis housed an economiser (124) of the independent secondary Rankinecycle.
 15. An installation for the generation of energy, according toclaim 4, in which the heat pump UAX (200) includes: a main Generator(201) of gaseous ammonia, acting as cold reservoir, which exchanges heatsolely with the Element (107), a secondary Generator (202), whichreceives a liquid phase from an ammonia Absorber (210), and sends theammonia vapour to some Compressors (203), while the remaining ammoniasolution is sent to the main Generator, at least two ammonia Compressors(203), connected in series, with cooling in between, which receiveammonia from the main (201) and secondary Generators (202) a compressedammonia Condenser (207) which receives the ammonia compressed and cooledin a supercritical ammonia Evaporator (209), and transmits the heat tothe secondary Generator (202), a supercritical ammonia Evaporator (209),a Pump (208) for ammonia condensate from the compressed ammoniaCondenser (209), which impels it to the ammonia Evaporator (209), whereammonia vapour is produced at supercritical pressure, an ammoniaAbsorber (210), which receives the vapour from the supercritical ammoniaEvaporator (209) and dissolves it in an aqueous phase, and a transferPump (215) which transfers the dilute ammonia solution from the mainGenerator (201) to the Absorber (210).
 16. An installation for thegeneration of energy, according to claim 15, in which the heat pump alsoincludes: a heat Exchanger (213/214) between a dilute ammonia solutionfrom the main Generator (201) and a concentrated ammonia solution fromthe Absorber (210), a Coil (211) housed inside the ammonia Evaporator(209), which harnesses the heat contained in the concentrated ammoniasolution from the Absorber (210), to produce supercritical ammonia, acooling Coil (206) for the compressed ammonia from the Compressors(203), which provides heat to the supercritical ammonia Evaporator(209).
 17. A procedure for the generation of energy based upon theCombined Cycle which is implemented using the installation defined inclaim
 2. 18. A procedure according to claim 17, which includesimplementing a constituent Brayton cycle, closed or based onoxy-combustion, regenerated by the action of the heat pump (UAX), whichuses water as thermal fluid and produces mechanical energy in ahigh-temperature Turbine (102), implementing a constituent Rankine cycleinterconnected with the foregoing Brayton cycle, and which exchangesmatter and energy with it, as both use water as common thermal fluid,and produces mechanical energy at a Turbine TAP (122), using a heat pumpUAX (200) which exchanges energy with the constituent Brayton cycle toregenerate it and absorb mechanical energy in certain compressors (203).19. A procedure according to claim 18, in which the water vapourcirculating through the element (107) condenses completely as aconsequence of the heat transmitted to the cold reservoir (201) of theheat pump UAX (200), leaving as gaseous reside only the incondensableCO₂ in the case that the cycle uses fuels other than hydrogen.
 20. Aprocedure according to claim 19, which includes: condensing in theelement (107): the water vapour at ambient pressure, relinquishing theheat obtained to the cold reservoir (201) of the heat pump UAX (200) orcondensing the water vapour and the CO₂ relinquishing the heat obtainedto the cold reservoir (201) of the heat pump UAX (200), and regeneratingwater vapour in the Reboiler (113) at a higher pressure than that atwhich it was condensed in the element (107), using the heat provided bythe hot reservoir (210) of the heat pump UAX (200).
 21. A procedureaccording to claim 17, in which the regeneration of the constituentBrayton cycle is conducted by the action of the heat pump UAX (200),recycling the vapour condensation heat at the temperature of the coldreservoir to subsequently return it to the cycle, by means of the hotreservoir, to regenerate water vapour at a higher pressure andtemperature than those at which it was previously condensed.
 22. Aprocedure according to claim 17, which includes: providing externalenergy from the essential heat Source (101), which is a pressurisedburner in the case of the semi-closed cycle, or a heat exchanger in thecase of the closed cycle.
 23. A procedure according to claim 17, which,without regard to the real losses, includes the use of a single heatsink, by which the cycle transmits heat to the outside.
 24. A procedureaccording to claim 23, in which a Condenser (128) of an independentsecondary Rankine cycle performs the function of heat sink.
 25. Aprocedure according to claim 17, which includes using a heat recoveryConduit (103), in which the remaining heat from the outlet of a TurbineTAT (102) is used to generate superheated vapour of the constituentbasic Rankine cycle.
 26. A procedure according to claim 17, whichincludes implementing an oxy-combustion Combined Cycle and which usesliquid or gaseous fuels, of general formula C_(x)H_(y)O_(z), either pureor mixed, where x, y and z take values corresponding to real chemicalcompounds which are capable of burning with oxygen.
 27. A procedureaccording to claim 25, which includes reducing the amount of vapourentering towards the heat Source (101), or towards the heat sources(101) and an element for the additional supply of heat (132), by meansof an auxiliary heat relief system made up of a Reheater (134) and aTurbine TPI (135), in such a way that an extraction of outlet vapourfrom the Turbine TAP (122) is performed, thus reducing the amount ofheat entering the CRC (103).
 28. A procedure according to claim 17,which includes preheating the water entering a Reboiler (113) by meansof an Element (112) with heat from the condensation of the vapour thattakes place in an Element (114).
 29. A procedure according to claim 28,which includes raising the pressure of the vapour supplied by theElement (112) and the pressure of the vapour from the Reboiler (113) andemerges from the condensation exchanger Element (114) using theadditional mechanical Compressors (115) and (117), connected in cascade,with intervening cooling and capable of supplying pressure sufficient tosend this vapour to the essential heat Source (101).
 30. A procedureaccording to claim 24, which includes: in the case that the CombinedPower Cycle is implemented as closed, or burns only hydrogen, to sendvapour directly from the heat recovery Conduit (103) to a Turbine TBP(127) of the secondary Rankine cycle, which operates under vacuumconditions provided by the Condenser (128), from where the condensate isreturned as feedwater to the constituent basic Rankine cycle.
 31. Aprocedure according to claim 17, which includes aspirating the outletgases from the Conduit (103), compressing them using a Fan (104) andsending them to a condensation heat exchanger Element (105), thusgenerating vapour in an Evaporator (125) of a secondary Rankine cycle.32. A procedure according to claim 19, in which: the heat pump UAX (200)is a refrigerating machine which functions by combining operations ofcompression and absorption, using NH₃ as thermal fluid and water assolvent, the main Generator (201) of the heat pump UAX (200) dischargesthe function of cold reservoir, absorbing the heat from the Element(107), exclusively, the only cold reservoir of the heat pump UAX (200)works at temperatures between 80° C. and 120° C., the ammonia Absorber(210) of the heat pump UAX (200) acts as the hot reservoir, transferringthe heat to the Reboiler (113), exclusively, in the heat pump UAX (200),the compression of the NH₃ vapour takes place, in successive stages withcooling in between, the compressed ammonia vapour Condenser (207) of theheat pump UAX (200) relinquishes all of the heat released by thesecondary Generator (202), and the supercritical ammonia Evaporator(209) of the heat pump UAX (200) generates NH₃ in supercritical statewith the heat supplied to it by the compressed ammonia cooling Elements(204) and (206) between stages of compression and with part of thelatent heat held by the concentrated solution which emerges hot from theammonia Absorber (210).